FOCUS REVIEW DOI: 10.1002/asia.201301594

Metal Complexes of Carbaporphyrinoid Systems Timothy D. Lash*[a]

Chem. Asian J. 2014, 9, 682 – 705

682

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Timothy D. Lash

www.chemasianj.org

Abstract: The cavities of carbaporphyrinoid systems provide unique environments for the formation of organometallic species. These systems commonly act as either dianionic or trianionic ligands, and may stabilize unusual oxidation states such as silverACHTUNGRE(III). Although the metalation of N-confused porphyrins has been explored in great detail, the formation of metallo-derivatives of other carbaporphyrinoids remains far less well explored. Nevertheless, exciting advances have been made on the metalation of carbaporphyrins, azuliporphyrins, benziporphyrins and related macrocycles. Keywords: azuliporphyrins · benziporphyrins · carbaporphyrins · N-confused porphyrins · neoconfused porphyrins

1. Introduction Carbaporphyrinoid systems are porphyrin-like compounds where one or more carbon atoms are placed within the macrocyclic cavity.[1–4] Although speculations on the formation of carboporphyrins 1, now known as N-confused porphyrins (NCPs, 1), were published in 1943,[5, 6] it was more than fifty years later that the first reports on these porphyrin isomers appeared in the literature.[7, 8] Following the development of a high-yielding method for the synthesis of tetraaryl-NCPs,[9] the chemistry of N-confused porphyrins has been widely investigated.[10, 11] Concurrent with these discoveries, related carbaporphyrinoid systems were reported including benziporphyrins 2,[12–14] oxybenziporphyrins 3,[13, 14] tropiporphyrins 4,[15] carbaporphyrins (e.g., 5),[16] and azuliporphyrins 6 (Figure 1).[12] Carbaporphyrinoid systems have unique properties and give insights into the aromatic characteristics of porphyrinoid structures.[14, 18, 19] The degree of aromatic character in these macrocycles varies considerably, and while carbaporphyrins 5 are highly diatropic, azuliporphyrins have reduced diatropicity, and benziporphyrins are essentially nonaromatic.[1–3] Porphyrin analogues of this type exhibit unusual reactivity, including the ability to generate organometallic derivatives under mild conditions.[1–3] Although these species resemble the organometallic complexes of pincer-type ligands,[20] the ordered equatorial arrangement of coordinating atoms provides a unique environment for metal binding. Furthermore, as pincer-type complexes are valuable catalytic species,[20] metalated carbaporphyrinoids show promise for applications in this arena. In an early report, tetratolyl-NCP was shown to react with nickel(II) chloride to give a stable nickel(II) complex,[8] and this observation spurred investigations into the metalation of NCPs and other carbaporphyrinoids.[1, 4, 11] By varying the carbaporphyrinoid framework, it is possible to modulate metalation reactions, and this approach has proven to be a fertile area for investigation. Much of the early work was carried out on NCPs, and a number of reviews on the metalation of NCPs have been

Figure 1. Selected carbaporphyrinoid systems.

published.[11, 21, 22] In this Focus Review, the metalation of other carbaporphyrinoids will be emphasized, although some of the results for NCPs are noted to provide a contrast to these studies.

2. Synthesis of Carbaporphyrinoid Systems Tetraaryl-NCPs were first obtained as by-products from the reaction of pyrrole with aromatic aldehydes.[7, 8] It was well known that benzaldehyde reacts with pyrrole under a variety of conditions to give meso-tetraphenylporphyrins, but it was not until 1994 that the formation of low yields of NCPs was noted.[7, 8] Subsequently, it was demonstrated that excellent yields of tetraphenyl-NCP could be obtained when pyrrole and benzaldehyde were reacted in the presence of methanesulfonic acid (Scheme 1).[9] The initial syntheses of related

[a] T. D. Lash Department of Chemistry Illinois State University Normal, Illinois 61790-4160 (USA) E-mail: [email protected]

Chem. Asian J. 2014, 9, 682 – 705

683

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Timothy D. Lash

www.chemasianj.org

Scheme 1. Synthesis of N-confused porphyrins.

carbaporphyrinoid sytems relied upon stepwise methods, and the “3 + 1” variant on the MacDonald condensation proved to be particularly effective in synthesizing novel porphyrinoid structures.[23] In this methodology, a tripyrrane 7 is condensed with a dialdehyde in the presence of an acid catalyst, and following an oxidation step the porphyrinoid system is generated (Scheme 2). This approach has been

Scheme 3. “3 + 1” Syntheses of carbaporphyrinoid systems.

thiophene, and selenophene dialdehydes to give oxa-, thia-, and selena-azuliporphyrins 9,[27, 31–33] while the reaction of 8 with indene dialdehyde 10 afforded the dicarbaporphyrinoid 11 (Scheme 3).[27] In addition, “2 + 2” MacDonald-type condensations have been used to prepare mono- and dicarbaporphyrinoids.[34, 35] More direct routes have been developed to synthesize tetraarylcarbaporphyrinoids. For instance, azulenes 12 were shown to react with pyrrole and benzaldehyde in the presence of boron trifluoride etherate to give, following oxidation with DDQ, tetraarylazuliporphyrins 13 (Scheme 4).[36–38] In addition, benzenedicarbinols 14 similarly

Scheme 2. MacDonald-type “3 + 1” syntheses of porphyrinoid structures.

applied to the synthesis of NCPs,[24, 25] porphyrinoids 2–6,[13–17, 26, 27] and related systems such as pyrazoloporphyrins,[28] carbachlorins,[29] and naphthiporphyrins.[30] Modified tripyrrane-like intermediates have also been utilized in the synthesis of heterocarbaporphyrins and dicarbaporphyrinoid systems. For instance, azulitripyrranes 8 reacted with furan,

Timothy D. Lash was born in Salisbury, England, on October 13th 1953. He received his Ph.D. degree under the guidance of Professor Anthony H. Jackson from the University of Wales, College of Cardiff, in 1979. In 1984, he joined the Department of Chemistry at Illinois State University as an Assistant Professor, and was promoted to the rank of Professor in 1993. He was subsequently awarded the title of Distinguished Professor in 2000. Professor Lash has published over 180 journal articles and three book chapters. His research has primarily focused on the synthesis, spectroscopy, aromatic characteristics, geochemistry, and biochemistry of porphyrins and related macrocyclic systems.

Chem. Asian J. 2014, 9, 682 – 705

Scheme 4. One-pot syntheses of carbaporphyrinoids.

react with pyrrole and aromatic aldehydes to give tetraarylbenziporphyrins 15 (Scheme 4).[39, 40]

3. N-Confused Porphyrins and Related Systems N-Confused porphyrins can act as dianionic or trianionic ligands to give organometallic derivatives. Reaction of 1 with nickel(II) chloride in refluxing chloroform/methanol gave the nickel(II) complex 16 where one of the NH protons has

684

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

Timothy D. Lash

Figure 2. Coordination modes exhibited by N-confused porphyrins.

type II, and other examples include CuIII,[46a] CoIII,[48] RhIII,[49] and Sb(V)[51] derivatives. In addition, some complexes (type III) possess a metal bound to an sp3-hybridized carbon atom. A complex of this type (20) was obtained by reacting 16 with methyl iodide (Scheme 5); a dimethylated complex 21 was also formed as a by-product.[52] In addition, many metalated species of type IV, which lack a carbon– metal bond, have been described including zinc,[53] manganese(II), and iron(II) derivatives.[54] The manganese(II) and iron(II) complexes reacted with molecular oxygen to give derivatives of type V.[54c] As NCPs can coordinate at the external nitrogen, and may form carbon–metal bonds to the aryl substituents, many additional coordination modes have been reported,[4] but studies of this type fall outside of the scope for this review. The metalation of meso-unsubstituted NCPs has also been investigated. NCP 22 reacted with nickel(II) acetate in DMF at 145 8C to give the nickel(II) complex 23 (Scheme 7).[24] This species showed greatly reduced aromatic character, but when TFA was added to a solution of 23 in CDCl3 a strong diamagnetic ring current was generated. An internal CH resonance was observed at 4.93 ppm, while the external meso-protons gave rise to four singlets between

Scheme 5. Nickel complexes of N-confused porphyrins.

been relocated onto the external nitrogen (Scheme 5).[8] This structure is cross-conjugated and exhibits greatly reduced aromatic characteristics. On the other hand, 1 reacts with silver(I) trifluoroacetate to afford the silverACHTUNGRE(III) complex 17 (Scheme 6).[41] In this case, the NCP acts as a tria-

Scheme 6. SilverACHTUNGRE(III) and goldACHTUNGRE(III) N-confused porphyrins.

nionic ligand and the silver(I) reactant is transformed into the AgACHTUNGRE(III) complex, presumably via the following disproportionation reaction: 3 Ag + !Ag3 + + 2 Ag0.[42] As the porphyrinoid unit retains an 18p electron delocalization pathway, 17 still has strongly diatropic properties. The related goldACHTUNGRE(III) complex 18 cannot be obtained directly from 1, but instead it is necessary to initially carry out a monobromination with N-bromosuccinimide to form 21-bromoNCP 19, and subsequent reaction with 3.3 equivalents of [AuClACHTUNGRE(SMe2)] then gives 18.[43] NCPs give rise to diverse coordination complexes ACHTUNGRE(Figure 2). Cross-conjugated complexes I include nickel(II) complexes 16 and derivatives of PdII,[44] PtII,[45] CuII,[46] MnIII,[47] CoII,[48] RhIV,[49] and MoII.[50] The silver and gold complexes 17 and 18 correspond to complex

Chem. Asian J. 2014, 9, 682 – 705

Scheme 7. Formation of a nickel(II) complex of a meso-unsubstituted Nconfused porphyrin and its protonation behavior.

685

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

Timothy D. Lash

9.37 and 10.01 ppm.[24] The new species was identified as a C-protonated nickel complex 24 that possessed an 18p electron delocalization pathway. Although the protonation is reversible, cation 24 slowly demetalates to give protonated NCP.[24] Subsequently, similar C-protonation processes were reported for the copper(II) and nickel(II) complexes of tetraphenyl-NCP.[46a] N-Methyl and N-phenyl NCPs 25 have also been prepared, and these readily formed the corresponding NiII and PdII complexes 26 and 27 (Scheme 8).[25]

Scheme 9. Formation of 21-substituted NCPs from a silverACHTUNGRE(III) complex.

The metalation of O-confused oxaporphyrins has also been investigated. Pyrrole-appended O-confused porphyrinoid 33 was easily metalated with nickel(II) chloride or palladium(II) chloride in the presence of anhydrous potassium carbonate to give the metallo-derivatives 34 a and 34 b, respectively (Scheme 10).[57] Porphyrinoid 33 is an aromatic species that exhibits a strong diamagnetic ring current, but the nickel(II) and palladium(II) complexes 34 are cross-conjugated and show substantially reduced diatropicity.[57] Reaction of 33 with silver(I) acetate in acetonitrile gave the fully aromatic silverACHTUNGRE(III) complex 35 a, but when ethanol was Scheme 8. Metalation of 2-substituted N-confused porphyrins.

Addition of TFA to solutions of these metallo-derivatives also gave aromatic C-protonated species 26H + and 27H + , respectively. A higher concentration of TFA was required to form the protonated palladium complexes 27H + compared to the nickel species 26H + , but the palladium complexes proved to be far more stable under acidic conditions. NCPs 25 reacted with silver(I) acetate to give the silverACHTUNGRE(III) complexes 28 where the 3-position had been oxidized to a carbonyl unit. These lactams proved to be highly diatropic compounds, and the proton NMR spectrum for a solution of 28 a in CDCl3 showed the meso-protons as four 1H singlets between 9.10 and 9.86 ppm. NCP 25 a also reacted with goldACHTUNGRE(III) acetate to give a low yield of the related goldACHTUNGRE(III) complex 29.[25] The metalated derivatives demonstrate modified reactivity that enables the synthesis of substituted NCPs. For instance, silverACHTUNGRE(III) NCP 17 reacted with dimethylamine to give the 21-dimethylamino-NCP 30,[55] while reaction with potassium diphenylphosphide afforded the 21-diphenylphosphanyl-NCP 31 (Scheme 9).[56] Oxidation with DDQ generated the related diphenylphosphoryl-NCP 32. Attempts to metalate 32 with silver(I) acetate led to elimination of the phosphoryl unit and the formation of the original silverACHTUNGRE(III) complex 17. Thiophosphorylation reactions were also reported in the presence of elemental sulfur (S8).[56]

Chem. Asian J. 2014, 9, 682 – 705

Scheme 10. Metalation of a pyrrole-appended O-confused oxaporphyrin.

686

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Timothy D. Lash

www.chemasianj.org

added to the reaction mixture, the related ethoxy-derivative 35 b was generated.[57] Protonation with TFA facilitated elimination of ethanol to give the cationic species 36. This system retained strongly diatropic properties due to electron donation from the pyrrole substituent (resonance structure 36’). In fact, the pyrrole unit now resembled a component of a pyrromethene rather than an isolated pyrrole.[57] Porphyrinoid 33 also reacted with copper(II) acetate in refluxing THF to give the copperACHTUNGRE(III) complex 37 in quantitative yield (Scheme 11).[58] This organometallic derivative also

Scheme 12. Formation of carbaporpholactones.

elimination of ethanol in the presence of TFA transformed the structure into the cationic species 45 (Scheme 12).[59] This slowly converted into the carbaporpholactone 46, possibly by initial nucleophilic attack from water followed by oxidation of the intermediary hydroxy species. It was suggested that the silverACHTUNGRE(III) complex was responsible for this oxidation and that silver(I) is lost during the reaction. The porphyrinoid lactone was easily remetalated with silver(I) acetate to give the silverACHTUNGRE(III) complex 47.[59] Reaction of 47 with methylamine or dimethylamine resulted in demetalation and the formation of amino-derivatives 48 (Scheme 13).[55] Similarly, reaction with sodium diphenylphosphide afforded the phosphine derivative 49.[60] This was easily oxidized with DDQ to produce the corresponding phosphine oxide 50, and further reaction with copper(II) acetate in the presence of air afforded the nonaromatic copper(II) complex 51. However, treatment of 50 with silver(I) acetate led to loss of the phosphoryl group and regeneration of the silverACHTUNGRE(III) complex 47.[60] S-Confused thiaporphyrin 52 reacted with cadmium(II) chloride in chloroform or zinc(II) chloride in THF to give metal complexes 53 a and 53 b in quantitative yields (Scheme 14).[61] The macrocycle acts as a monoanionic ligand in these cases, and the metal cation requires the presence of an axial chloride. Coupling between the protons and carbon-13 nuclei of the thiophene unit and the NMR-active cadmium isotopes (111Cd and 113Cd) indicates that there is a strong interaction between the metal and thiophene fragments despite the absence of a formal carbon–metal bond. This interpretation is supported by the X-ray crystallographic data. Organometallic nickel(II) and palladium(II) com-

Scheme 11. Reactions of copperACHTUNGRE(III) O-confused oxaporphyrins.

gave an NMR spectrum that was consistent with an aromatic species, although the downfield shifts due to the external pyrrolic protons were reduced compared to those in silverACHTUNGRE(III) complex 35 a. This difference was attributed to contributions from a paramagnetic canonical form.[58] In the presence of oxygen, 37 was converted into the copper(II) complex 38, and further exposure to O2 led to an oxidative cleavage that gave a tripyrrinone complex 39 (Scheme 11). Bromination of 38 generated the aromatic cation 40 that resembled the silverACHTUNGRE(III) derivative 36. Treatment of copperACHTUNGRE(III) complex 37 with hydrogen peroxide in the presence of KOH inserted an oxygen atom into the macrocyclic core to give 41, and this could be demetalated with hydrochloric acid to afford the hydroxyporphyrinoid 42. Ethoxy-O-confused porphyrinoid 43 reacted with silver(I) acetate to give the aromatic silverACHTUNGRE(III) organometallic complex 44, and

Chem. Asian J. 2014, 9, 682 – 705

687

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Timothy D. Lash

www.chemasianj.org

Scheme 13. Synthesis of 21-substituted carbaporpholactones from a silverACHTUNGRE(III) derivative. Scheme 15. Metalation of pyrazoloporphyrins.

56 or 57 gave protonated species 56H + and 57H + that exhibited virtually a complete loss of aromatic character, and the proton NMR spectra in TFA/CDCl3 showed a substantial upfield shift to the meso-proton resonances. The aromatic character exhibited by free base 55 and metal complexes 56 and 57 can be attributed to dipolar resonance contributors such as 55’, 56’, and 57’ that possess 18p electron delocalization pathways.[28] In the protonated species 56H + and 57H + , this type of canonical form would be disfavored because it would be necessary to place two positive charges next to one another (see structures 56’H + and 57’H + ).[28]

4. Neo-Confused Porphyrins and Related Systems

Scheme 14. Metalation of an S-confused thiaporphyrin.

Recently, a new type of porphyrin isomer 58 was reported where a pyrrole unit is connected to a meso-bridge carbon atom.[62] This system, which retains an 18p electron delocalization pathway, has been named neo-confused porphyrin. In addition, neo-confused corroles (norroles, 59), were synthesized in independent investigations.[63] These macrocycles have an internal CH and therefore can be considered to be carbaporphyrinoid systems. In the initial study, benzo-neoconfused porphyrin 60 was shown to react with nickel(II) acetate in acetonitrile to give the nickel(II) organometallic derivative 61 a in 90 % yield (Scheme 16).[62a] The proton NMR spectrum for 61 a showed that the metal complex has comparable diatropic character to free-base neo-confused porphyrin 60, although both species are significantly less aromatic than true porphyrins. An example of a neo-confused porphyrin 62 without a fused benzene ring has also been reported,[64] and this porphyrinoid has been shown to form

plexes 54 can also be obtained from 52,[4] although details of this work are not currently available. Further confused porphyrinoids 55, which possess a pyrazole subunit, reacted with nickel(II) acetate or palladium(II) acetate to give the organometallic derivatives 56 and 57, respectively (Scheme 15).[28] The conjugation pathway in pyrazoloporphyrins 55 has been disrupted by the presence of a cross-conjugated pyrazole unit, and the diatropicity of this system is much reduced compared to porphyrins. The proton NMR spectra for 55 showed the meso-protons between 6.8 and 7.9 ppm, while the internal CH appeared between 5.2 and 5.9 ppm.[28] Metalation increased the downfield shifts for the meso-protons, which now showed up between 7.3 and 8.1 ppm. However, the X-ray structure for palladium complex 57 was consistent with a primarily localized p-bonding system.[28a] Addition of TFA to solutions of

Chem. Asian J. 2014, 9, 682 – 705

688

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Timothy D. Lash

www.chemasianj.org

indole unit in the free-base form 66 was rotated relative to the plane due to the tripyrrolic component by 35.18.[66]

5. Carbaporphyrins Carbaporphyrins are porphyrin analogues where one or more of the nitrogens have been replaced by carbon atoms. Examples of mono- and dicarbaporphyrins have been prepared,[16, 26, 67, 68] although metalated derivatives have only been reported for monocarbaporphyrins. Much of this work has been conducted using readily available benzocarbaporphyrins 67. Initial attempts to metalate benzocarbaporphyrins with first-row transition-metal cations such as NiII, CuII, and CoII were unsuccessful,[69] although 67 undergoes a regioselective oxidation in the presence of 500 equivalents of ironACHTUNGRE(III) chloride in alcohol solvents to give ketal derivatives 68 (Scheme 18).[70] However, reaction of benzocarba-

Scheme 16. Metalation of neo-confused porphyrins.

stable nickel(II) and palladium(II) complexes 63.[65] Although initial attempts to prepare a palladium(II) complex of 60 were unsuccessful, 61 b has now been isolated in pure form.[65] These metalated derivatives are all stable compounds and have been characterized by X-ray crystallography.[65] Metalation studies on norrole have not as yet been reported. However, neo-confused bilane 64 was cyclized by sequential treatment with p-chloranil and CuACHTUNGRE(OAc)2·H2O to give the copperACHTUNGRE(III) benzonorrole complex 65 in 68 % yield (Scheme 17).[66] This was reductively demetalated with zinc metal and hydrochloric acid to afford the free-base benzonorrole 66 in 94 % yield.[66] X-ray crystallography showed that the copperACHTUNGRE(III) complex 65 was nearly planar, while the

Scheme 18. Regioselective oxidation and metalation of benzocarbaporphyrins.

porphyrins at room temperature with silver(I) acetate generated the corresponding silverACHTUNGRE(III) complexes 69 in excellent yields.[71, 72] The silverACHTUNGRE(III) complexes retain highly diatropic characteristics and the proton NMR spectra for 69 showed the resonances for the meso-protons downfield near 10 ppm. The UV/Vis spectra for these stable organometallic derivatives were also porphyrin-like, showing a strong Soret band at 437 nm.[71, 72] The X-ray crystal structure for a benzocarbaporphyrin 67 showed that the indene unit was canted by approximately 158 relative to the mean macrocyclic plane.[71] However, the silverACHTUNGRE(III) cation replaces the three inner hydrogens to give nearly planar metallo-derivatives 69. A meso-unsubstituted benzocarbaporphyrin also reacted with goldACHTUNGRE(III) acetate to give low yields of the goldACHTUNGRE(III) complex 70 (Scheme 18).[72] meso-Tetraarylbenzocarbaporphyrins 71 similarly reacted with silver(I) acetate to give the silverACHTUNGRE(III) complexes 72 (Scheme 19).[72] In this system, meso-substitu-

Scheme 17. Synthesis and demetalation of a copperACHTUNGRE(III) benzonorrole.

Chem. Asian J. 2014, 9, 682 – 705

689

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

Timothy D. Lash

formation of 77. It may be that the alkyl group migration involves a [1,5]sigmatropic rearrangement, but a stepwise mechanism involving a transient Pd-alkyl species is also possible. The palladium(II) complexes 77 retain strongly diatropic characteristics. In the proton NMR spectrum for 77 a, the meso-protons appeared downfield as two 2H singlets at 9.56 and 10.27 ppm, while the internal methyl group gave an upfield 3H resonance at 3.21 ppm.[73] Related palladium(II) complexes have been obtained from p-benzi- and 1,4naphthiporphyrins (Scheme 21).[74] Treatment of p-benzipor-

Scheme 19. Metalation of meso-tetrasubstituted benzocarbaporphyrins.

tion appears to protect the macrocycle from oxidative degradation, and treatment with goldACHTUNGRE(III) acetate in refluxing pyridine gave the goldACHTUNGRE(III) derivatives 73 in 67–83 % yield.[72] Benzocarbaporphyrin 67 a reacted with methyl or ethyl iodide in the presence of potassium carbonate to give a mixture of N-alkyl and C-alkyl benzocarbaporphyrins 74 and 75, respectively (Scheme 20).[73] The major product 74 was

Scheme 21. Formation of palladium(II) carbaporphyrins from p-benziand 1,4-naphthiporphyrins.

phyrin 78 with palladium(II) chloride in acetonitrile gave the palladium(II) complex 79. Evidence was presented to demonstrate that the palladium cation interacts with the phenylene unit in an h2-fashion. When 79 was treated with potassium carbonate in acetonitrile, a ring contraction occurred producing the palladium(II) carbaporphyrin complexes 80 a and 80 b in a 3.5:1 ratio. The anti-addition product 81 was identified as an intermediate by proton NMR spectroscopy. It was proposed that initial loss of the chloride ligand, followed by addition of hydroxide, afforded 81 (Scheme 22). Elimination of H2, followed by a ring contraction involving a 1,2-hydride shift would give 80 a. Alternatively, cheletropic loss of CO would produce the palladium complex 80 b. The palladium complex of 1,4-naphthiporphyrin 82 similarly underwent a ring contraction to afford the corresponding palladium(II) benzocarbaporphyrins 83. The C-formyl derivative 83 a was isolated in 22 % yield, but the

Scheme 20. Formation of palladium(II) complexes from N-alkylated benzocarbaporphyrins.

reacted with palladium(II) acetate in refluxing acetonitrile in an attempt to prepare the palladium(II) complex 76 (Scheme 20). However, the metalation reaction occurred with concomitant alkyl group migration to generate the Calkyl palladium(II) derivatives 77.[73] At short reaction times, 76 appeared to be the major product, but attempts to purify this species by column chromatography invariably led to the

Chem. Asian J. 2014, 9, 682 – 705

690

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Timothy D. Lash

www.chemasianj.org

acetate to give the palladium(II) complex 87 in 80 % yield.[76] X-ray diffraction analysis demonstrated that palladium(II) complexes 85 b and 87 are both nearly planar.[75, 76]

6. Azuliporphyrins Azuliporphyrins 88 are an interesting class of porphyrin analogues that exhibit substantially reduced diatropic character compared to carbaporphyrins.[17, 27] The diminished aromaticity for these macrocycles is due to the presence of a crossconjugated azulene moiety, and the inner CH proton is shifted upfield in the proton NMR spectra of azuliporphyrins;[27, 32] it appears near + 3 ppm rather than at a value of 7 ppm that is commonly seen for carbaporphyrins such as 67. Unlike carbaporphyrins, azuliporphyrins act as dianionic organometallic ligands. Azuliporphyrins 88 have been shown to react with nickel(II) acetate, palladium(II) acetate, or platinum(II) chloride to give good yields of the corresponding metallo-complexes 89 (Scheme 24).[77, 78] These

Scheme 22. Proposed mechanism for the ring contraction of a palladium(II) benziporphyrin.

21-unsubstituted version 83 b was only formed in trace amounts.[74] Heterocarbaporphyrins have also been synthesized, and oxacarbaporphyrins have been shown to act as dianionic ligands.[75, 76] 23-Oxacarbaporphyrin 84 was reacted with nickel(II) acetate, palladium(II) acetate, or platinum(II) chloride in DMF to give the corresponding organometallic derivatives 85 (Scheme 23).[75] Although 85 a and 85 b were isolated

Scheme 24. Metalation of azuliporphyrins.

stable complexes also demonstrate significant diatropicity, and the meso-protons are shifted further downfield than the values observed for free-base azuliporphyrins. The largest effects are observed for the palladium(II) complexes, which appear to be the most aromatic macrocycles for this series, while the platinum complexes 89 c gave smaller downfield shifts compared to 89 a and 89 b. The meso-protons for 89 c showed sidebands due to transannular coupling by 195Pt (4JPt,H = 4.4–5.6 Hz). meso-Tetraarylazuliporphyrins 90 were similarly shown to react with NiACHTUNGRE(OAc)2, PdACHTUNGRE(OAc)2, and PtCl2 to give the related organometallic derivatives 91 (Scheme 24).[78] Azuliporphyrins 88 were also converted into iridiumACHTUNGRE(III) complexes (Scheme 25).[79] Reaction of 88 with [IrClCOD]2 in refluxing o- or p-xylene gave the benzoyliridiumACHTUNGRE(III) complexes 92, albeit in relatively low

Scheme 23. Metalation of oxacarbaporphyrins.

in 53 % and 70 % yield, respectively, the platinum complex 85 c was only obtained in 5 % yield. As expected, these metallo-derivatives retained strongly diatropic characteristics. 22-Oxacarbaporphyrin 86 also reacted with palladium(II)

Chem. Asian J. 2014, 9, 682 – 705

691

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

Timothy D. Lash

Scheme 25. Formation of iridiumACHTUNGRE(III) azuliporphyrins.

Scheme 27. Oxidative metalation of azuliporphyrins with copper(II) salts.

Scheme 28. Metalation of an azulene-base pincer ligand. Scheme 26. Proposed mechanism for the formation of benzoyl iridiumACHTUNGRE(III) azuliporphyrins.

the nonaromatic oxo-derivative 97, but this could be remetalated to give nickel(II), palladium(II), or platinum(II) complexes 98. Coordination complexes of an azulene-based pincer ligand have also been reported.[81] Specifically, azulene bisthioamide 99 was shown to react with palladium chloride and lithium chloride in refluxing methanol to give the organometallic palladium complex 100 a (Scheme 28). In addition, 99 reacted with [PtCl2ACHTUNGRE(PhCN)2] in acetonitrile to give the related platinum complex 100 b.[81] While they are not carbaporphyrinoid derivatives, these structures clearly have similar features to metalated azuliporphyrins such as 89 b and 89 c.

yields. A tert-butyl substituted complex (92 d) gave crystals that were suitable for X-ray diffraction analysis, and these results confirmed the presence of an axial aroyl unit.[79] The incorporation of a solvent molecule in this fashion was unexpected, but a mechanism to explain this result was proposed (Scheme 26). It was suggested that the iridiumACHTUNGRE(III) chloride macrocyclic complex 93 was initially formed and that this reacted with the solvent to form the benzyl iridiumACHTUNGRE(III) species 94. Further oxidation with molecular oxygen would give the peroxide intermediate 95 that could eliminate a molecule of water to produce the observed carbonyl unit. The proton NMR spectra for these complexes showed large upfield shifts for the benzene protons because they overlie the azuliporphyrin p-system.[79] Tetraarylazuliporphyrins reacted with copper(II) acetate in DMF or pyridine to give copper(II) complexes 96 (Scheme 27).[80] Even though the reactions were carried out under nitrogen, an oxidative metalation had taken place. When the reaction was carried out in the presence of 18O-labeled water, no incorporation of the heavy isotope was observed, and thus the oxygen atom appears to originate from molecular oxygen. X-ray crystallography showed that the structure was highly distorted and the azulene ring was tilted by nearly 538 relative to the mean macrocyclic plane.[80] Treatment of 96 with 10 % TFA in chloroform gave

Chem. Asian J. 2014, 9, 682 – 705

7. Benziporphyrins, Naphthiporphyrins, and Confused Pyriporphyrins Benziporphyrins are porphyrin analogues with a benzene ring in place of a pyrrole unit.[12–14, 82] This system can act as a monoanionic or dianionic ligand. Reaction of meso-tetraarylbenziporphyrins 101 with palladium(II) chloride in refluxing acetonitrile gave the corresponding organometallic derivatives 102 in 49–70 % yield (Scheme 29).[39, 40] Similarly, tetraphenylbenziporphyrin reacted with platinum(II) chloride in refluxing benzonitrile to give 103 in 20 % yield.[39] However, treatment of 101 with silver(I) acetate did not

692

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

Scheme 29. Metalation and selective oxidation of meso-tetraarylbenziporphyrins.

Timothy D. Lash

Scheme 31. Reactions of a copperACHTUNGRE(III) benzene-containing macrocycle.

afford a metal complex but instead gave a regioselective oxidation to afford the 21-acetoxy-derivative 104.[39] In a related reaction, 99 was shown to react with AgBF4 in pyridine to give the 22-pyridiniumyl derivative 105 (Scheme 30).[83] It was proposed that the silverACHTUNGRE(III) benziporphyrin 106 is initially formed, followed by reversible axial coordination of pyridine and reductive elimination of silver(I) (Scheme 30).[83] Transformations of these types are not limit-

placed by various nucleophiles such as methanol, giving methoxy derivative 109, and pyridone, producing adduct 110.[84] Tetraazacalix[1]arene[3]pyridines such as 111 also exhibit similar reactivity.[85] Treatment of 111 with copper(II) perchlorate afforded the copperACHTUNGRE(III) complex 112, and further reaction with a variety of nucleophiles gave substitution products 113 (Scheme 32).[85] Tetraphenylbenziporphyrin 101

Scheme 32. Preparation of a copperACHTUNGRE(III) tetraazacalix[1]arene[3]pyridine and the formation of nucleophilic substitution products.

reacted with copper(II) chloride under anaerobic conditions to give the dimeric copper(II) complex 114 where selective chlorination onto the internal carbon had taken place (Scheme 33).[86] Reaction of 101 with zinc chloride, cadmium chloride, or mercury salts gave the coordination complexes 115 a–c,[87] and ferric bromide similarly reacted with 101 and 2,6-lutidine in refluxing THF to give the corresponding iron(II) complex 115 d (Scheme 34).[87] Several of these complexes were characterized by X-ray crystallography, and evi-

Scheme 30. Formation of a 21-pyridiniumylbenziporphyrin.

ed to benziporphyrins, and similar chemistry has been observed for other benzene-containing macrocycles. For instance, triazamacrocycles such as 107 react with copper(II) salts to give copperACHTUNGRE(III) organometallic complexes 108 (Scheme 31).[84] The reaction involves a disproportionation to form CuIII and CuI. The chelated copperACHTUNGRE(III) can be dis-

Chem. Asian J. 2014, 9, 682 – 705

693

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

forms with 18p electron delocalization pathways.[92, 93] Tetraaryldimethoxybenziporphyrins 120 reacted with silver(I) acetate to give the 21-acetoxy derivatives 121 (Scheme 35).[93b] The proton NMR spectra for 121 (R = H) showed the acetate methyl group protons near 1.3 ppm, thus demonstrating that this unit is shielded by the macrocyclic p-system. Addition of TFA gave rise to dicationic species where the acetate resonance shifted upfield to 0.5 ppm, while the external pyrrolic protons shifted downfield by 0.5– 0.8 ppm, and this was attributed to the system taking on significant diatropic characteristics. These effects were much reduced when a methyl group was present between the two methoxy substituents, and this was attributed to the methyl unit preventing the OMe units from lying coplanar with the aromatic ring, which is necessary for effective electron donation.[93b] Reaction of 120 with nickel(II) acetate in refluxing chloroform/methanol gave the nickel(II) derivatives 122 in 74–81 % yield,[93] while treatment with palladium(II) acetate in refluxing acetonitrile gave the corresponding palladium complexes 123 in 73–82 % yield (Scheme 35).[93b] The proton NMR spectra for these compounds indicated that they were significantly diatropic. For instance, the nickel(II) complex 122 (R = H, Ar = Ph), showed the pyrrolic protons shifted downfield to between 7.24 and 7.66 ppm. The effect was larger in the corresponding palladium(II) complex where the pyrrole resonances appeared between 7.30 and 7.74 ppm, and this suggests that the palladium complex is more diatropic than the nickel complex. This may be due to the palladium version taking on a more planar conformation. An X-ray crystal structure was obtained for the nickel(II) complex 122 (R = H, Ar = Ph), and the macrocycle was shown to have a highly distorted saddle-shaped geometry.[93b] As was the case for acetoxy derivatives 121, the diatropic character of chelates 122 and 123 was reduced when a methyl group was present between the two methoxy units.

Scheme 33. Formation of a copper benziporphyrin dimer.

dence for agostic interactions with the arene unit were presented.[87] Benziporphodimethenes such as 116 also reacted with NiCl2, ZnCl2, and CdCl2 to give the corresponding metalated derivatives 117 (Scheme 34).[87] Dimeric silver(I) complexes of benziporphodimethenes have also been reported.[88] In addition, a related benziporphodimethene has shown promise as a selective zinc cation fluorescence switch-on sensor.[89] A zinc benziporphodimethene was also used as a building block to construct multidimensional nanostructure arrays.[90] Tetraphenylbenziporphyrin 101 reacted with nickel(II) chloride to give a similar chloronickel(II) complex 118, but this further reacted in refluxing acetonitrile to give the organometallic derivative 119.[87] The formation of 119 was speeded up by the presence of a small amount of anhydrous potassium carbonate. Treatment of 119 with dry HCl in chloroform transformed the complex back into 118 (Scheme 34).[91] Dimethoxybenziporphyrins such as 120 have also been synthesized,[92, 93] and these porphyrinoids show a degree of overall aromatic character. This was attributed to electron donation from the OMe units, which stabilized canonical

Scheme 34. Formation of NiII, ZnII, CdII, HgII and FeII complexes of benziporphyrins and benziporphodimethenes.

Chem. Asian J. 2014, 9, 682 – 705

Timothy D. Lash

Scheme 35. Metalation and selective oxidation of dimethoxybenziporphyrins.

694

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Timothy D. Lash

www.chemasianj.org

The metalation of meso-unsubstituted benziporphyrins has also been investigated.[30] Benziporphyrin 124 reacted with nickel(II) acetate in refluxing DMF to give the nickel(II) complex 125 a in 42 % yield (Scheme 36). The palladium(II) complex 125 b was similarly obtained in 35 % yield by reacting 124 with palladium(II) acetate in refluxing acetonitrile.[30] The proton NMR spectra for 125 a showed the meso-protons as two 2H singlets at 7.16 and 7.48 ppm, while the palladium complex 125 b showed these resonances at 7.35 and 7.72 ppm. These data indicate that these simple metallobenziporphyrins have a degree of overall diatropicity, possibly due to dipolar resonance contributors such as 125’ that possess 18p electron delocalization pathways. Again, the palladium(II) complex showed larger downfield shifts than the nickel(II) derivative.[30] Diphenylbenziporphyrins 126 were also shown to give good yields of the corresponding palladium(II) complexes 127 when treated with palladium(II) acetate in refluxing acetonitrile.[94] X-ray diffraction analysis of the tert-butyl substituted complex 127 b showed that the macrocycle was a somewhat distorted, slightly saddled structure, where the benzene unit was tilted by nearly 208 relative the tripyrrolic component (Scheme 36).[94] Naphthiporphyrin 128 similarly reacted with palladium(II) acetate to give the metalated complex 129.[30] The X-ray crystal structure for this complex demonstrated

that the macrocycle was slightly saddled but otherwise relatively planar.[30] The metalation of p-benziporphyrins 130 has also been investigated. Reaction of 130 with cadmium(II) chloride, zinc(II) chloride, or nickel(II) chloride gave metal complexes 131 with an appended chloro group (Scheme 37).[87, 95]

Scheme 36. Metalation of meso-unsubstituted benzi- and naphthiporphyrins.

Scheme 38. Metalation and ring-opening of a 9,10-anthriporphyrin.

Chem. Asian J. 2014, 9, 682 – 705

Scheme 37. Metalation of p-benziporphyrins.

The phenylene unit is rotated out of the plane, but evidence for weak metal–arene h2-interactions has been presented. The palladium complex of tetraphenyl-p-benziporphyrin rearranges in the presence of potassium carbonate to give palladium(II) carbaporphyrins (see earlier; Scheme 21). A related anthriporphyrin 132 has also been prepared.[96] X-ray crystallography demonstrated that the anthracene ring is pivoted by > 708 out of the plane described by the tripyrrolic component of the structure. Reaction with palladium(II) chloride in acetonitrile/dichloromethane gave palladium(II) complex 133 a (Scheme 38) in virtually quantitative yield. Treatment with silver tetrafluoroborate, followed by sodium bromide, afforded the corresponding bromide 133 b. In the presence of potassium carbonate and molecular oxygen, 133 a and 133 b were converted into ring-opened palladium(II) tripyrrinone complexes 134. A 16 % yield was reported for palladium complex 134 a. In the course of this reaction, the coordinated halogen atom is transferred onto the anthracene ring.[96]

695

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

Timothy D. Lash

N-confused pyriporphyrins such as 135 and 136 have also been synthesized,[97, 98] and these porphyrinoids can be considered to be azabenziporphyrins. Certainly, the coordination cavities for these macrocycles are essentially the same as the one found in benziporphyrins. Pyriporphyrin 135 was shown to react with FeBr2 and collidine in THF to give iron(II) complexes 137 and 138 (Scheme 39).[97] Treatment of 137 with bromine gave the corresponding ironACHTUNGRE(III) complex, while exposure to oxygen afforded the five-coordinate ironACHTUNGRE(III) complex 139. Pyriporphyrin 136 reacted with palladium(II) acetate in refluxing acetonitrile to give the corresponding palladium(II) complex 140 (Scheme 39).[98] Addition of TFA afforded the related cation 140H + . As expected, the proton NMR spectra for 140 and 140H + were consistent with nonaromatic porphyrinoids.[98]

Scheme 40. SilverACHTUNGRE(III) complexes of oxybenzi- and oxynapthiporphyrins.

dianionic or a trianionic ligands. Oxybenziporphyrins 141 reacted with silver(I) acetate to give the corresponding silverACHTUNGRE(III) complexes 142 (Scheme 40).[30, 99] Similarly, oxynaphthiporphyrins 143 were transformed into the silverACHTUNGRE(III) organometallic derivatives 144.[30, 99] These complexes retained the highly diatropic characteristics of the parent macrocycles. When 141 a was reacted with one equivalent of palladium(II) chloride in the presence of potassium carbonate, an aromatic anion 145 was generated (Scheme 41).[100] Although this species can be written as a cross-conjugated phenolate anion 145’, the proton NMR spectrum showed the meso-protons downfield between 9.08 and 10.37 ppm, values that are consistent with a strongly diatropic species possessing an 18p electron delocalization pathway.[100] Addition of one equivalent of TFA converted the green solution of 145 into a red-violet solution corresponding to the palladium(II) hydroxybenziporphyrin 146. The diatropic character for this species was much reduced compared to 145, as dipolar canonical forms such as 146’ are less favorable.[100] The corresponding platinum complex 147 was prepared similarly (Scheme 41), but this species was highly insoluble.[1] When the sample was loaded onto a silica column, the hydroxy derivative 148 eluted with chloroform. The proton NMR spectrum for this species in [D6]DMSO showed the meso-proton resonances between 7.89 and 9.11 ppm, thus indicating that the complex has a degree of aromatic character.[1] The anionic palladium(II) complex 145 is an ambident nucleophile.[100] Treatment of 145 with acetic anhydride and pyridine gave the acetate 149 a, while reaction with p-toluenesulfonyl chloride afforded the related p-toluenesulfonate

Scheme 39. Metalation of N-confused pyriporphyrins.

8. Oxybenziporphyrins, Oxynaphthiporphyrins, and Tropiporphyrins The introduction of a 2-hydroxy group onto the benziporphyrin skeleton facilitates a tautomerization that produces an aromatic porphyrinoid ketone designated as oxybenziporphyrin 141 (Scheme 40).[13, 14] Oxybenziporphyrins can act as

Chem. Asian J. 2014, 9, 682 – 705

696

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

Timothy D. Lash

Scheme 42. Substitution of a palladium(II) oxybenziporphyrin.

Scheme 41. Formation of palladium(II) and platinum(II) oxybenziporphyrins.

149 b (Scheme 42). However, substitution could also occur on the interior carbon atom. Reaction of 145 with methyl iodide generated the aromatic C-methylated product 150 a, while treatment with n-butyl iodide afforded a mixture of the C-alkylation product 150 b and the O-alkylation product 151 (Scheme 42). Surprisingly, the C-alkylation products 150 were highly diatropic, possibly due to dipolar resonance contributors such as 150’. The proton NMR spectrum for 150 a showed four 1H singlets for the meso-protons at 9.20, 9.22, 9.25, and 10.40 ppm, while the internal methyl group gave rise to an upfield 3H singlet at 2.00 ppm. Protonation with TFA afforded the aromatic cation 150H + .[100] Tetraaryloxybenziporphyrins 151 have also been synthesized.[101] Reaction of 151 with silver(I) acetate in pyridine generated the silverACHTUNGRE(III) complexes 152, while treatment with goldACHTUNGRE(III) acetate afforded the corresponding goldACHTUNGRE(III) derivatives 153 (Scheme 43). Oxybenziporphyrins 151 are aromatic compounds but the diamagnetic ring currents are somewhat diminished compared to the meso-unsubstituted porphyrinoids 141. The internal CH appears near 3 ppm in the proton NMR spectra for 151, compared to values of approximately 7 ppm for 141. SilverACHTUNGRE(III) complexes 152 show enhanced diatropic character compared to 151, as judged by the signif-

Chem. Asian J. 2014, 9, 682 – 705

Scheme 43. Metalation of meso-tetraaryloxybenziporphyrins.

icant downfield shifts for the pyrrolic protons. Steric crowding due to the aryl substituents is likely to cause significant distortions to the macrocycle, but the metal complexes can potentially draw the subunits into a more planar arrangement. These downfield proton NMR shifts for the pyrrolic protons are slightly larger for goldACHTUNGRE(III) complexes 153, implying that these derivatives are slightly more aromatic.[101] Oxa-oxybenziporphyrin 154 has also been shown to react with palladium(II) chloride in benzonitrile to give the palladium(II) complex 155 (Scheme 44).[102] The replacement of an NH with an oxygen atom transforms the system from

697

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

Timothy D. Lash

(Scheme 46).[107] Reaction of 160 with copper(II) and copper(I) salts gave more complicated results and afforded a copper(I) complex 163 with a pyridiniumyl group attached to a benzene ring (Scheme 46).[107] It was proposed that copper(II)-assisted elimination of hydride resulted in the formation of the CuI center. The formation of 163 resembles the generation of a pyridiniumyl-substituted porphyrinoid 105 from the reaction of benziporphyrin with silver(I) acetate and pyridine (Scheme 30). Attempts to recrystallize 163

Scheme 44. Metalation of an oxa-oxybenziporphyrin and a highly oxidized benziporphyrin system.

being a potentially trianionic ligand into a dianionic ligand. Further oxidized benziporphyrin systems have also been investigated, and porphyrinoid 156 acts as a trianionic ligand.[103] Treatment of 156 with silver(I) acetate at room temperature in dichloromethane/methanol gave the silverACHTUNGRE(III) complex 157 in 87 % yield (Scheme 44).[103] Both 155 and 157 retained the aromatic characteristics of the parent ligands. Tropiporphyrins 158 also act as trianionic ligands and react with silver(I) acetate and DBU in refluxing pyridine to give the related silverACHTUNGRE(III) complexes 159 (Scheme 45).[104] Although these derivatives have significant diatropic character, the macrocycle is quite distorted. A single-crystal X-ray diffraction analysis for 159 b showed that the tripyrrolic component was somewhat ruffled, but the cycloheptatriene ring was severely twisted.[104]

Scheme 45. SilverACHTUNGRE(III) complexes of tropiporphyrin.

9. Benziphthalocyanines Phthalocyanine analogues with benzene rings in place of one or two of the isoindolene units have been known for many years.[105, 106] The dibenziphthalocyanine system is known as dicarbahemiporphyrazine 160, while the monobenzi-version can be considered to be a benziphthalocyanine 161.[106] Silver(I) acetate was shown to react with dicarbahemiporphyrazine 160 to give the silver(I) complex 162

Chem. Asian J. 2014, 9, 682 – 705

Scheme 46. Metalation of dicarbahemiporphyrazine and benziphthalocyanine.

698

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

with dichloromethane in the presence of air resulted in demetalation to form 164. Reaction of 160 with diethylzinc, followed by crystallization from hexanes/pyridine, gave the zinc complex 165 (Scheme 46).[108] However, the reaction of benziphthalocyanine 161 with diethylzinc involved the nucleophilic addition of an ethyl group to produce zinc complex 166.[108] Treatment of 161 with Co2(CO)8 in pyridine gave the cobalt(II) organometallic derivative 167, but this readily air oxidizes to the related cobaltACHTUNGRE(III) complex 168 (Scheme 47).[109] However, reaction with cobalt(II) acetate

Timothy D. Lash

gen atoms to give an overall neutral complex. Dicarbahemiporphyrazine 160 similarly reacted with NiACHTUNGRE(COD)2 to give the nickel(II) complex 171, and this reacted with molecular oxygen to afford the nonplanar phenolate complex 172 (Scheme 48).[110] 10. Miscellaneous Porphyrinoid Systems In addition to carbaporphyrins, an example of a nonaromatic carbacorrole 173 has been reported.[111] Reaction of 173 with silver(I) tetrafluoroborate or copper(II) acetate gave silverACHTUNGRE(III) complex 174 a and copperACHTUNGRE(III) derivative 174 b, respectively (Scheme 49).[111] The metal insertion was

Scheme 49. Synthesis of silverACHTUNGRE(III) and copperACHTUNGRE(III) organometallic complexes of a carbacorrole and the formation of an oxacorrole. Scheme 47. Cobalt complexes of benziphthalocyanine.

associated with a rearrangement to give fully conjugated carbacorrole species. The proton NMR spectra for 174 a and 174 b showed pronounced downfield shifts for the external protons consistent with fully aromatic structures. As would be expected, the protons on the internal tolyl substituents were shifted upfield. For instance, solutions of silverACHTUNGRE(III) complex 174 in CDCl3 at 180 K showed the o-tolyl protons at 4.46 ppm. SilverACHTUNGRE(III) derivative 174 a was characterized by X-ray crystallography, and this showed that the macrocycle was substantially distorted from planarity. SilverACHTUNGRE(III) complex 174 a reacted with aqueous HCl in the presence of O2 to give oxocorrole 175. During the course of this reaction, the interior benzylic unit and the silverACHTUNGRE(III) cation are lost.[111] A number of porphyrinoid systems with properties similar to carbaporphyrinoids have been investigated. For instance, thiaethyneporphyrin 176 has been synthesized where an acetylene unit replaces a pyrrole ring.[112] As 176 does not have an internal CH, this is not considered to be carbaporphyrinoid system. However, the coordination chemistry for this macrocycle is insightful. Reaction of 176 with copper(II) acetate gives a copper(II) complex 177 a that shows significant h2-interactions with the triple bond (Scheme 50).[113] Similar complexes 177 b and 177 c were obtained by reacting 177 with nickel(II) or palladium(II) acetate.[114] Reduction of palladium complex 177 c with sodium borohydride gave the porphyrinoid anion 178, but this species could only be characterized by spectroscopic methods. Deazaporphyrin 179, commonly known as vacataporphyrin, can be consid-

tetrahydrate in DMF resulted in hydration of the macrocycle in addition to forming the cobaltACHTUNGRE(III) derivative 169.[109] Carbaphthalocyanines of this type are far more reactive than phthalocyanines because they are nonaromatic compounds and commonly undergo addition reactions onto the macrocycle. NiACHTUNGRE(COD)2 in DMF/methanol reacted with 161 to give the nickel(II) complex 170 (Scheme 48).[110] As is the case for 167, two protons are relocated onto bridging nitro-

Scheme 48. Nickel(II) derivatives of dicarbahemiporphyrazine and benziphthalocyanine.

Chem. Asian J. 2014, 9, 682 – 705

699

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Timothy D. Lash

www.chemasianj.org

Scheme 52. Metalation of a [22]porphyrinACHTUNGRE(3.1.1.3).

albeit in low yield (Scheme 50).[117] The ruthenium forms a s-bond to the internal azulene carbon and thereby retains the symmetry of the parent macrocycle. 21-Pallada-23-telluraporphyrin 186 is also worthy of note.[118] Ditelluraporphyrin 187 was found to react with palladium(II) acetate in the presence of triethylamine to give the porphyrinoid 186 with an embedded palladole ring (Scheme 53). This system clearly ties in with palladium complexes such as 178 and 181. The macrocycle shows strongly aromatic characteristics and at room temperature rapidly interconverts between the two equivalent forms 186 and 186’. It was proposed that an intermediary symmetrical transition state 186# is involved in this transformation (Scheme 53).[118]

Scheme 50. Metalation of thiaethyneporphyrins and a dithiaethyneazuliporphyrin.

ered to be a triphyrinACHTUNGRE(6.1.1). However, the presence of internal CH units gives this system some similarities to carbaporphyrinoids. Vacataporphyrin 179 reacted with PdII, CdII, NiII, and ZnII halides to give the corresponding metal complexes 180 (Scheme 51).[115] Exposure of the palladium(II) complex

Scheme 53. Synthesis of a 21-pallada-23-telluraporphyrin. Scheme 51. Metalation of vacataporphyrin.

11. Dicarbaporphyrinoid Systems to UV light resulted in the formation of the organometallic complex 181, and further rearrangements to give other palladium(II) derivatives were reported.[115] [22]PorphyrinACHTUNGRE(3.1.1.3) 182 has a similar coordination core and reacted with palladium(II) chloride to give the palladium(II) complex 183 (Scheme 52).[116] Again, the porphyrin skeleton has undergone E,Z-isomerization to accommodate the palladium cation. The dithiaethyneazuliporphyrin 184 has been prepared and this system reacted with Ru3(CO)12 in refluxing chlorobenzene to give the ruthenium(II) complex 185,

Chem. Asian J. 2014, 9, 682 – 705

The metalation of dicarbaporphyrinoid systems has been little studied, but several examples of these types of complexes have been reported. cis-Doubly N-confused porphyrin (cis-N2CP, 188) reacted with silver(I) acetate in 10 % pyridine/chloroform to give silverACHTUNGRE(III) complex 189 a in quantitative yield (Scheme 54).[119] Copper(II) acetate similarly reacted with 188 to afford the copperACHTUNGRE(III) derivative 189 b.[119] These organometallic complexes can be protonated onto an external nitrogen, and halide anion binding to the resulting cationic species has been investigated.[120] cis-N2CP 188 also

700

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

Timothy D. Lash

Scheme 54. Metalation of cis-doubly N-confused porphyrins.

Scheme 56. Formation of a palladium(II) complex of an adj-diazuliporphyrin.

reacted with palladium(II) acetate in refluxing toluene to give the palladium(II) species 190 that had undergone arylation onto an internal carbon atom (Scheme 54).[121] A mixture of meta- and para-tolyl isomers were observed in a ratio of 2:1.[121] trans-N2CPs 191 also reacted with copper(II) acetate to give good yields of the corresponding copperACHTUNGRE(III) organometallic derivatives 192 (Scheme 55).[122]

of processes are by no means unique. In particular, N-heterocyclic carbenes readily form organometallic derivatives. Heterocycles built up from four imidazolium subunits are known, and metallo-derivatives such as 195 and 196 have been investigated.[123, 124] While these structures do not have macrocyclic conjugation pathways, they provide a similar coordination framework to carbaporphyrinoids.

Scheme 55. CopperACHTUNGRE(III) derivatives of trans-doubly N-confused porphyrins.

11. Expanded Carbaporphyrinoids

Diazuliporphyrins such as 193 were isolated as monoprotonated species.[34] This adj-dicarbaporphyrinoid was found to react with palladium(II) acetate in refluxing acetonitrile to give the palladium(II) complex 194 in 26 % yield (Scheme 56).[34] This polar organometallic derivative can be written as a series of dipolar or tetrapolar canonical forms. The X-ray crystal structure for 194 showed that the porphyrinoid skeleton was slightly saddled and confirmed the presence of the centrally coordinated palladium ion.[34] In the proton NMR spectrum of 194, the meso-protons were observed downfield at 7.9 (1 H), 8.8 (2 H), and 10.0 ppm (1 H), and this result suggests that this complex is somewhat diatropic. The aromatic properties of 194 were attributed to resonance contributors such as 194’ that possess 18p electron delocalization pathways.[34] The formation of carbaporphyrinoid complexes often involves the formation of carbon–metal bonds, but these sorts

Chem. Asian J. 2014, 9, 682 – 705

Expanded carbaporphyrinoid systems have also been investigated. For instance, benzocarbasapphyrin 197[125, 126] and azulisapphyrin 198[126] have been reported and these systems

have been contrasted to carbaporphyrinoids such as 67 and 88. However, the formation of metallo-derivatives of these systems has not as yet been investigated. Dibenziporphyri-

701

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

Timothy D. Lash

Scheme 57. Metalation of expanded carbaporphyrinoids.

noid 199 has been reacted with Rh2(CO)4Cl2 in benzene to give the bis-rhodium(I) complex 200 in high yield (Scheme 57).[127] Reaction of 199 with nickel(II) or palladium(II) acetylacetonate gave bis-nickel(II) complex 201 a and bis-palladium(II) derivative 201 b, respectively.[127] Similarly, diindene porphyrinoids 202 reacted with zinc acetate in methanol to give the bridged bis-zinc complexes 203.[128] Expanded porphyrinoid systems often possess inverted heterocyclic rings that place CH units within the macrocyclic cavity.[129, 130] This phenomenon blurs the boundaries between carbaporphyrinoid systems and expanded porphyrinoid structures. Hexaarylhexaphyrins 204 provide particularly illustrative examples as they commonly take on a conformation that places four CH units within the macrocycle.[131] In essence, this provides two binding pockets that resemble dicarbaporphyrinoid structures. Hexaphyrin 204 reacted with NaAuCl4 to give a mixture of the mono-gold(II) complex 205 (16 %) and the bis-goldACHTUNGRE(III) complex 206 a (14 %) (Scheme 58).[132] These derivatives closely resemble silverACHTUNGRE(III) and goldACHTUNGRE(III) carbaporphyrins 72 and 73. Reduction of 205 or 206 with sodium borohydride gave the related antiaromatic [28]hexaphyrin complexes 207.[132] This chemistry has been extended to the preparation of mixed complexes with AgACHTUNGRE(III)-AuIII,[132] CuIII-AuIII,[133] RhIII-AuIII,[133] and IrIIIAuIII[134] (206 b–e). A series of bis-gold complexes 208 of the reduced antiaromatic [28]hexaphyrin(1.1.1.1.1.1) system have also been prepared.[135] Nickel(II), palladium(II), and platinum(II) complexes 209 were obtained by reacting 204

Chem. Asian J. 2014, 9, 682 – 705

Scheme 58. Metalation of meso-hexaarylhexaphyrins(1.1.1.1.1.1).

with NiACHTUNGRE(acac)2, PdCl2, or PtCl2, respectively.[136] The chiral Mçbius aromatic palladium(II) complex 209 b has been resolved to give the individual enantiomers by using HPLC on a chiral stationary phase.[137] Treatment of 209 b with tris(4bromophenyl)aminium hexachloroantimonate induced a molecular topology change to give the Hckel aromatic complex 210 a.[138] Reaction of 210 a with copper(II) acetate gave the PdII-CuIII [26]hexaphyrin complex 210 b in 90 % yield, while reaction with silver triflate in acetonitrile afforded the PdII-AgACHTUNGRE(III) complex 210 c in 93 % yield.[138] Treatment of 210 a with [PdACHTUNGRE(OCOCF3)2] generated the aromatic bis-palladium(II) complex 211, and this was readily deprotonated with tetrabutylammonium fluoride to produce the corresponding dianion (Scheme 58).[139] Doubly N-confused hexaphyrin 212 reacted with [AuClACHTUNGRE(SMe2)] to give the goldACHTUNGRE(III) complex 213, and further treatment with [PtCl2ACHTUNGRE(PhCN)2] afforded the mixed PtII-AuIII complex 214 (Scheme 59).[140]

702

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Timothy D. Lash

www.chemasianj.org

porphyrinoid complexes as catalysts for cyclopropanation reactions.[49a, 142] The fact that the reactivity of these species can be modulated by using different carbaporphyrinoid frameworks is also beneficial. It is anticipated that many additional advances will be made in this dynamic research area in the future.

Acknowledgements Our work in this area has been supported by the National Science Foundation, most recently under grant no. CHE-1212691, and the Petroleum Research Fund, administered by the American Chemical Society.

Scheme 59. Metalation of doubly-N-confused hexaphyrins.

[1] T. D. Lash in Handbook of Porphyrin Science—With Applications to Chemistry, Physics, Material Science Engineering, Biology and Medicine, Vol. 16, (Ed. K. M. Kadish, K. M. Smith, R. Guilard), World Scientific Publishing, Singapore, 2012, pp. 1 – 329. [2] a) T. D. Lash, Synlett 2000, 279 – 295; b) T. D. Lash, Eur. J. Org. Chem. 2007, 5461 – 5481. [3] T. D. Lash in The Porphyrin Handbook, Vol. 2 (Eds.: K. M. Kadish, K. M. Smith, R. Guilard), Academic Press, San Diego, CA, 2000, pp. 125 – 199. [4] M. Pawlicki, L. Latos-Grazynski in Handbook of Porphyrin Science—With Applications to Chemistry, Physics, Material Science Engineering, Biology and Medicine, Vol. 2 (Eds.: K. M. Kadish, K. M. Smith, R. Guilard), World Scientific Publishing, Singapore, 2010, pp. 103 – 192. [5] S. Aronoff, M. Calvin, J. Org. Chem. 1943, 8, 205 – 223. [6] M. O. Senge, Angew. Chem. 2011, 123, 4360 – 4365; Angew. Chem. Int. Ed. 2011, 50, 4272 – 4277. [7] H. Furuta, T. Asano, T. Ogawa, J. Am. Chem. Soc. 1994, 116, 767 – 768. [8] P. J. Chmielewski, L. Latos-Grazynski, K. Rachlewicz, T. Glowiak, Angew. Chem. 1994, 106, 805 – 808; Angew. Chem. Int. Ed. Engl. 1994, 33, 779 – 781. [9] G. R. Geier, III, D. M. Haynes, J. S. Lindsey, Org. Lett. 1999, 1, 1455 – 1458. [10] a) H. Furuta, H. Maeda, A. Osuka, Chem. Commun. 2002, 1795 – 1804; b) A. Srinivasan, H. Furuta, Acc. Chem. Res. 2005, 38, 10 – 20; c) M. Toganoh, H. Furuta, Chem. Commun. 2012, 48, 937 – 954. [11] M. Toganoh, H. Furuta in Handbook of Porphyrin Science—With Applications to Chemistry, Physics, Material Science Engineering, Biology and Medicine, Vol. 2, (Ed.: K. M. Kadish, K. M. Smith, R. Guilard), World Scientific Publishing: Singapore, 2010, pp. 103 – 192. [12] K. Berlin, E. Breitmaier, Angew. Chem. 1994, 106, 1356 – 1357; Angew. Chem. Int. Ed. Engl. 1994, 33, 1246 – 1247. [13] T. D. Lash, Angew. Chem. 1995, 107, 2703 – 2705; Angew. Chem. Int. Ed. Engl. 1995, 34, 2533 – 2535. [14] T. D. Lash, S. T. Chaney, D. T. Richter, J. Org. Chem. 1998, 63, 9076 – 9088. [15] T. D. Lash, S. T. Chaney, Tetrahedron Lett. 1996, 37, 8825 – 8828. [16] T. D. Lash, M. J. Hayes, Angew. Chem. 1997, 109, 868 – 870; Angew. Chem. Int. Ed. Engl. 1997, 36, 840 – 842. [17] T. D. Lash, S. T. Chaney, Angew. Chem. 1997, 109, 867 – 868; Angew. Chem. Int. Ed. Engl. 1997, 36, 839 – 840. [18] T. D. Lash, J. Porphyrins Phthalocyanines 2011, 15, 1093 – 1115. [19] T. D. Lash, J. Porphyrins Phthalocyanines 2012, 16, 423 – 433. [20] M. E. van der Boom, D. Milstein, Chem. Rev. 2003, 103, 1759 – 1792. [21] J. D. Harvey, C. J. Ziegler, Coord. Chem. Rev. 2003, 247, 1 – 19. [22] P. J. Chmielewski, L. Latos-Grazynski, Coord. Chem. Rev. 2005, 249, 2510 – 2533. [23] T. D. Lash, Chem. Eur. J. 1996, 2, 1197 – 1200.

Other examples include the Mçbius aromatic palladium(II) porphyrinoids 215 and 216.141 These organometallic structures illustrate the rich chemistry of expanded porphyrin

systems, but many other examples of these types of complexes can be found in the literature. As expanded porphyrins are somewhat peripheral to the topic of this review, no attempt has been made to cover this area in detail.

12. Conclusions Carbaporphyrinoid systems have produced a wide range of metallo-derivatives, and they have proven to be exemplary ligands in the formation of organometallic derivatives. By providing a well-ordered cavity, metalation reactions occur that would not necessarily take place in open structures. In addition, a wide range of carbaporphyrinoid ligands are now available for study, each of which has unique reactivity and may favor the formation of organometallic species at different oxidation states. The ease with which late transition metal ions are incorporated into carbaporphyrinoid structures suggests that these metalated species could have value in the design of catalytic systems. Indeed, some successes have been reported in the use of rhodium and cobalt carba-

Chem. Asian J. 2014, 9, 682 – 705

703

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

[24] T. D. Lash, D. T. Richter, C. M. Shiner, J. Org. Chem. 1999, 64, 7973 – 7982. [25] T. D. Lash, A. L. Von Ruden, J. Org. Chem. 2008, 73, 9417 – 9425. [26] a) T. D. Lash, M. J. Hayes, J. D. Spence, M. A. Muckey, G. M. Ferrence, L. F. Szczepura, J. Org. Chem. 2002, 67, 4860 – 4874; b) T. D. Lash, K. M. Bergman, J. Org. Chem. 2012, 77, 9774 – 9783. [27] T. D. Lash, D. A. Colby, S. R. Graham, S. T. Chaney, J. Org. Chem. 2004, 69, 8851 – 8864. [28] a) T. D. Lash, A. M. Young, A. L. Von Ruden, G. M. Ferrence, Chem. Commun. 2008, 6309 – 6311; b) A. M. Young, A. L. Von Ruden, T. D. Lash, Org. Biomol. Chem. 2011, 9, 6293 – 6305. [29] M. J. Hayes, T. D. Lash, Chem. Eur. J. 1998, 4, 508 – 511. [30] T. D. Lash, A. M. Young, J. M. Rasmussen, G. M. Ferrence, J. Org. Chem. 2011, 76, 5636 – 5651. [31] S. R. Graham, D. A. Colby, T. D. Lash, Angew. Chem. 2002, 114, 1429 – 1432; Angew. Chem. Int. Ed. 2002, 41, 1371 – 1374. [32] T. D. Lash, J. A. El-Beck, G. M. Ferrence, J. Org. Chem. 2007, 72, 8402 – 8415. [33] T. D. Lash, J. A. El-Beck, G. M. Ferrence, Org. Biomol. Chem. 2014, 12, 316 – 329. [34] Z. Zhang, G. M. Ferrence, T. D. Lash, Org. Lett. 2009, 11, 101 – 104. [35] a) T. D. Lash, D. A. Colby, A. S. Idate, R. N. Davis, J. Am. Chem. Soc. 2007, 129, 13800 – 13801; b) T. D. Lash, A. D. Lammer, A. S. Idate, D. A. Colby, K. White, J. Org. Chem. 2012, 77, 2368 – 2381. [36] D. A. Colby, T. D. Lash, Chem. Eur. J. 2002, 8, 5397 – 5402. [37] T. D. Lash, D. A. Colby, G. M. Ferrence, Eur. J. Org. Chem. 2003, 4533 – 4548. [38] J. A. El-Beck, T. D. Lash, Eur. J. Org. Chem. 2007, 3981 – 3190. [39] M. Ste˛pien´, L. Latos-Grazynski, Chem. Eur. J. 2001, 7, 5113 – 5117. [40] T. D. Lash, V. R. Yant, Tetrahedron 2009, 65, 9527 – 9535. [41] H. Furuta, T. Ogawa, Y. Uwatoko, K. Araki, Inorg. Chem. 1999, 38, 2676 – 2682. [42] C. Brckner, C. A. Barta, R. P. BriÇas, J. A. Krause Bauer, Inorg. Chem. 2003, 42, 1673 – 1680. [43] M. Toganoh, T. Niino, H. Furuta, Chem. Commun. 2008, 4070 – 4072. [44] H. Furuta, N. Kubo, H. Maeda, T. Ishizuka, A. Osuka, H. Nanami, T. Ogawa, Inorg. Chem. 2000, 39, 5424 – 5425. [45] a) H. Furuta, K. Youfu, H. Maeda, A. Osuka, Angew. Chem. 2003, 115, 2236 – 2238; Angew. Chem. Int. Ed. 2003, 42, 2186 – 2188; b) P. J. Chmielewski, I. Schmidt, Inorg. Chem. 2004, 43, 1885 – 1894; c) D.-H. Won, M. Toganoh, H. Uno, H. Furuta, Dalton Trans. 2009, 6151 – 6158. [46] a) P. J. Chmielewski, L. Latos-Grazynski, I. Schmidt, Inorg. Chem. 2000, 39, 5475 – 5482; b) H. Maeda, Y. Ishikawa, T. Matsuda, A. Osuka, H. Furuta, J. Am. Chem. Soc. 2003, 125, 11822 – 11823. [47] D. S. Bohle, W.-C. Chen, C.-H. Hung, Inorg. Chem. 2002, 41, 3334 – 3336. [48] J. D. Harvey, C. J. Ziegler, Chem. Commun. 2004, 1666 – 1667. [49] a) T. Niino, M. Toganoh, B. Andrioletti, H. Furuta, Chem. Commun. 2006, 4335 – 4337; b) A. Srinivasan, M. Toganoh, T. Niino, A. Osuka, H. Furuta, Inorg. Chem. 2008, 47, 11305 – 11313. [50] J. D. Harvey, J. L. Shaw, R. S. Herrick, C. J. Ziegler, Chem. Commun. 2005, 4663 – 4665. [51] J.-C. Liu, T. Ishizuka, A. Osuka, H. Furuta, Chem. Commun. 2003, 1908 – 1909. [52] P. J. Chmielewski, L. Latos-Grazynski, J. Chem. Soc. Perkin Trans. 2 1995, 503 – 509. [53] H. Furuta, T. Ishizuka, A. Osuka, J. Am. Chem. Soc. 2002, 124, 5622 – 5623. [54] a) W.-C. Chen, C.-H. Hung, Inorg. Chem. 2001, 40, 5070 – 5071; b) K. Rachlewicz, S.-L. Wang, J.-L. Ko, C.-H. Hung, L. Latos-Grazynski, J. Am. Chem. Soc. 2004, 126, 4420 – 4431; c) C.-H. Hung, S.L. Wang, J.-L. Ko, C.-H. Peng, C.-H. Hu, M.-T. Lee, Org. Lett. 2004, 6, 1393 – 1396. [55] N. Grzegorzek, M. Pawlicki, L. Latos-Grazynski, J. Org. Chem. 2009, 74, 8547 – 8553. [56] N. Grzegorzek, L. Latos-Grazynski, L. Szterenberg, Org. Biomol. Chem. 2012, 10, 8064 – 8075.

Chem. Asian J. 2014, 9, 682 – 705

Timothy D. Lash

[57] M. Pawlicki, L. Latos-Grazynski, Chem. Eur. J. 2003, 9, 4650 – 4660. [58] M. Pawlicki, I. Kanska, L. Latos-Grazynski, Inorg. Chem. 2007, 46, 6575 – 6584. [59] M. Pawlicki, L. Latos-Grazynski, J. Org. Chem. 2005, 70, 9123 – 9130. [60] N. Grzegorzek, M. Pawlicki, L. Szterenberg, L. Latos-Grazynski, J. Am. Chem. Soc. 2009, 131, 7224 – 7225. [61] M. J. Chmielewski, M. Pawlicki, N. Sprutta, L. Szterenberg, L. Latos-Grazynski, Inorg. Chem. 2006, 45, 8664 – 8671. [62] a) T. D. Lash, A. D. Lammer, G. M. Ferrence, Angew. Chem. 2011, 123, 9892 – 9895; Angew. Chem. Int. Ed. 2011, 50, 9718 – 9721; b) D. I. AbuSalim, T. D. Lash, Org. Biomol. Chem. 2013, 11, 8306 – 8323. [63] K. Fujino, Y. Hirata, Y. Kawabe, T. Morimoto, A. Srinivasan, M. Toganoh, Y. Miseki, A. Kudo, H. Furuta, Angew. Chem. 2011, 123, 6987 – 6991; Angew. Chem. Int. Ed. 2011, 50, 6855 – 6859. [64] R. Li, G. M. Ferrence, T. D. Lash, Chem. Commun. 2013, 49, 7537 – 7539. [65] R. Li, M. S. Thesis, Illinois State University, 2013. [66] M. Toganoh, Y. Kawabe, H. Uno, H. Furuta, Angew. Chem. 2012, 124, 8883 – 8886; Angew. Chem. Int. Ed. 2012, 51, 8753 – 8756. [67] D. I. AbuSalim, T. D. Lash, J. Org. Chem. 2013, 78, 11535 – 11548. [68] a) T. D. Lash, J. L. Romanic, M. J. Hayes, J. D. Spence, Chem. Commun. 1999, 819 – 820; b) T. D. Lash, A. D. Lammer, G. M. Ferrence, Angew. Chem. 2012, 124, 11029 – 11033; Angew. Chem. Int. Ed. 2012, 51, 10871 – 10875. [69] M. J. Hayes, J. D. Spence, T. D. Lash, Chem. Commun. 1998, 2409 – 2410. [70] T. D. Lash, M. A. Muckey, M. J. Hayes, D. Liu, J. D. Spence, G. M. Ferrence, J. Org. Chem. 2003, 68, 8558 – 8570. [71] M. A. Muckey, L. F. Szczepura, G. M. Ferrence, T. D. Lash, Inorg. Chem. 2002, 41, 4840 – 4842. [72] T. D. Lash, D. A. Colby, L. F. Szczepura, Inorg. Chem. 2004, 43, 5258 – 5267. [73] T. D. Lash, Org. Lett. 2011, 13, 4632 – 4635. [74] a) B. Szyszko, L. Latos-Grazynski, L. Szterenberg, Angew. Chem. 2011, 123, 6717 – 6721; Angew. Chem. Int. Ed. 2011, 50, 6587 – 6591; b) B. Szyszko, L. Latos-Grazynski, Organometallics 2011, 30, 4354 – 4363. [75] a) D. Liu, T. D. Lash, Chem. Commun. 2002, 2426 – 2427; b) D. Liu, G. M. Ferrence, T. D. Lash, J. Org. Chem. 2004, 69, 6079 – 6093. [76] P. Jain, G. M. Ferrence, T. D. Lash, J. Org. Chem. 2010, 75, 6563 – 6573. [77] S. R. Graham, G. M. Ferrence, T. D. Lash, Chem. Commun. 2002, 894 – 895. [78] T. D. Lash, D. A. Colby, S. R. Graham, G. M. Ferrence, L. F. Szczepura, Inorg. Chem. 2003, 42, 7326 – 7338. [79] T. D. Lash, K. Pokharel, M. Zeller, G. M. Ferrence, Chem. Commun. 2012, 48, 11793 – 11795. [80] D. A. Colby, G. M. Ferrence, T. D. Lash, Angew. Chem. 2004, 116, 1370 – 1373; Angew. Chem. Int. Ed. 2004, 43, 1346 – 1349. [81] J. Kuwabara, G. Munezawa, K. Okamoto, T. Kanbara, Dalton Trans. 2010, 39, 6255 – 6261. [82] M. Ste˛pien´, L. Latos-Grazynski, Acc. Chem. Res. 2005, 38, 88 – 98. [83] M. Ste˛pien´, L. Latos-Grazynski, Org. Lett. 2003, 5, 3379 – 3381. [84] a) X. Ribas, D. A. Jackson, B. Donnadieu, J. Maha, T. Parella, R. Xifra, B. Hedman, K. O. Hodgson, A. Llobet, T. D. P. Stack, Angew. Chem. 2002, 114, 3117 – 3120; Angew. Chem. Int. Ed. 2002, 41, 2991 – 2994; b) L. M. Huffman, S. S. Stahl, J. Am. Chem. Soc. 2008, 130, 9196 – 9197; c) A. E. King, L. M. Huffman, A. Casitas, M. Costas, X. Ribas, S. S. Stahl, J. Am. Chem. Soc. 2010, 132, 12068 – 12073. [85] a) B. Yao, D.-X. Wang, Z.-T. Huang, M.-X. Wang, Chem. Commun. 2009, 2899 – 2901; b) Z.-L. Wang, L. Zhao, M.-X. Wang, Org. Lett. 2011, 13, 6560 – 6563; c) B. Yao, Z.-L. Wang, H. Zhang, D.-X. Wang, L. Zhao, M.-X. Wang, J. Org. Chem. 2012, 77, 3336 – 3340; d) H. Zhang, L. Zhao, D.-X. Wang, M.-X. Wang, Org. Lett. 2013, 15, 3836 – 3839.

704

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemasianj.org

[86] C.-H. Hung, F.-C. Chang, C.-Y. Lin, K. Rachlewicz, M. Ste˛pien´, L. Latos-Grazynski, G.-H. Lee, S.-M. Peng, Inorg. Chem. 2004, 43, 4118 – 4120. [87] M. Ste˛pien´, L. Latos-Grazynski, L. Szterenberg, J. Panek, Z. Latajka, J. Am. Chem. Soc. 2004, 126, 4566 – 4580. [88] G.-F. Chang, C.-H. Wang, H.-C. Lu, L.-S. Kan, I. Chao, W. H. Chen, A. Kumar, L. Lo, M. A. C de La Rosa, C.-H. Hung, Chem. Eur. J. 2011, 17, 11332 – 11343. [89] C.-H. Hung, G.-F. Chang, A. Kumar, G.-F. Lin, L.-Y. Luo, W.-M. Ching, E. W.-G. Diau, Chem. Commun. 2008, 978 – 980. [90] C. Huang, Y. Li, J. Yang, N. Cheng, H. Liu, Y. Li, Chem. Commun. 2010, 46, 3161 – 3163. [91] M. Ste˛pien´, L. Latos-Grazynski, L. Szterenberg, Inorg. Chem. 2004, 43, 6654 – 6662. [92] D. T. Richter, T. D. Lash, Tetrahedron 2001, 57, 3657 – 3673. [93] a) J. T. Szymanski, T. D. Lash, Tetrahedron Lett. 2003, 44, 8613 – 8616; b) T. D. Lash, J. T. Szymanski, G. M. Ferrence, J. Org. Chem. 2007, 72, 6481 – 6492. [94] T. D. Lash, A. M. Toney, K. M. Castans, G. M. Ferrence, J. Org. Chem. 2013, 78, 9143 – 9152. [95] M. Ste˛pien´, L. Latos-Grazynski, J. Am. Chem. Soc. 2002, 124, 3838 – 3839. [96] B. Szyszko, L. Latos-Grazynski, L. Szterenberg, Chem. Commun. 2012, 48, 5004 – 5006. [97] a) R. Mys´liborski, L. Latos-Graz˙yn´ski, Eur. J. Org. Chem. 2005, 5039 – 5048; b) R. Mys´liborski, K. Rachlewicz, L. Latos-Graz˙yn´ski, Inorg. Chem. 2006, 45, 7828 – 7834. [98] T. D. Lash, K. Pokharel, J. M. Serling, V. R. Yant, G. M. Ferrence, Org. Lett. 2007, 9, 2863 – 2866. [99] T. D. Lash, J. M. Rasmussen, K. M. Bergman, D. A. Colby, Org. Lett. 2004, 6, 549 – 552. [100] M. Ste˛pien´, L. Latos-Grazynski, T. D. Lash, L. Szterenberg, Inorg. Chem. 2001, 40, 6892 – 6900. [101] J. A. El-Beck, T. D. Lash, Org. Lett. 2006, 8, 5263 – 5266. [102] S. Venkatraman, V. G. Anand, S. K. Pushpan, J. Sankar, T. K. Chandrashekar, Chem. Commun. 2002, 462 – 463. [103] a) K. Miyake, T. D. Lash, Chem. Commun. 2004, 178 – 179; b) T. D. Lash, K. Miyake, L. Xu, G. M. Ferrence, J. Org. Chem. 2011, 76, 6295 – 6308. [104] K. M. Bergman, G. M. Ferrence, T. D. Lash, J. Org. Chem. 2004, 69, 7888 – 7897. [105] R. P. Linstead, J. Chem. Soc. 1953, 2873 – 2884. [106] C. J. Ziegler in Handbook of Porphyrin Science - With Applications to Chemistry, Physics, Material Science Engineering, Biology and Medicine, Vol. 17, (Eds.: K. M. Kadish, K. M. Smith, R. Guilard), World Scientific Publishing: Singapore, 2012, pp. 113 – 238. [107] R. Wu, A. Cetin, W. S. Durfee, C. J. Ziegler, Angew. Chem. 2006, 118, 5798 – 5801; Angew. Chem. Int. Ed. 2006, 45, 5670 – 5673. [108] E. S. Bonner, J. T. Engle, S. Sripothongak, C. J. Ziegler, Dalton Trans. 2010, 46, 1932 – 1934. [109] A. C¸etin, S. Sripothongnak, M. Kawa, W. S. Durfee, C. J. Ziegler, Chem. Commun. 2007, 4289 – 4290. [110] S. Sripothongnak, N. Barone, C. J. Ziegler, Chem. Commun. 2009, 4584 – 4586. [111] J. Skonieczny, L. Latos-Graz˙yn´ski, L. Szterenberg, Chem. Eur. J. 2008, 14, 4861 – 4874. [112] A. Berlicka, L. Latos-Graz˙yn´ski, T. Lis, Angew. Chem. 2005, 117, 5422 – 5425; Angew. Chem. Int. Ed. 2005, 44, 5288 – 5291. [113] N. Grzegorzek, E. Nojman, L. Szterenberg, L. Latos-Graz˙yn´ski, Inorg. Chem. 2013, 52, 2599 – 2606. [114] E. Nojman, A. Berlicka, L. Szterenberg, L. Latos-Graz˙yn´ski, Inorg. Chem. 2012, 51, 3247 – 3260. [115] a) E. Pacholska-Dudziak, J. Skonieczny, M. Pawlicki, L. Szterenberg, Z. Ciunik, L. Latos-Graz˙yn´ski, J. Am. Chem. Soc. 2008, 130,

Chem. Asian J. 2014, 9, 682 – 705

[116] [117] [118]

[119] [120] [121] [122] [123]

[124]

[125] [126] [127]

[128] [129] [130] [131]

[132] [133] [134] [135] [136] [137] [138] [139] [140]

[141]

[142]

Timothy D. Lash

6182 – 6195; b) E. Pacholska-Dudziak, J. Skonieczny, M. Pawlicki, L. Szterenberg, L. Latos-Graz˙yn´ski, Inorg. Chem. 2005, 44, 8794 – 8803. L. Xu, G. M. Ferrence, T. D. Lash, Org. Lett. 2006, 8, 5113 – 5116. A. Berlicka, N. Sprutta, L. Latos-Graz˙yn´ski, Chem. Commun. 2006, 3346 – 3348. E. Pacholska-Dudziak, M. Szczepaniak, A. Ksiazek, L. Latos-Graz˙yn´ski, Angew. Chem. 2013, 125, 9066 – 9071; Angew. Chem. Int. Ed. 2013, 52, 8898 – 8903. H. Furuta, H. Maeda, A. Osuka, J. Am. Chem. Soc. 2000, 122, 803 – 807. H. Maeda, T. Morimoto, A. Osuka, H. Furuta, Chem. Asian J. 2006, 1, 832 – 844. H. Furuta, H. Maeda, A. Osuka, M. Yasutake, T. Shinmyozu, Y. Ishikawa, Chem. Commun. 2000, 1143 – 1144. H. Maeda, A. Osuka, H. Furuta, J. Am. Chem. Soc. 2003, 125, 15690 – 15691. F. E. Hahn, V. Langenhahn, T. Lgger, T. Pape, D. L. Van, Angew. Chem. 2005, 117, 3825 – 3829; Angew. Chem. Int. Ed. 2005, 44, 3759 – 3763. H. M. Bass, S. A. Cramer, J. L. Price, D. M. Jenkins, Organometallics 2010, 29, 3235 – 3238; S. Meyer, I. Klawitter, S. Demeshko, E. Bill, F. Meyer, Angew. Chem. 2013, 125, 935 – 939; Angew. Chem. Int. Ed. 2013, 52, 901 – 905. T. D. Lash, D. T. Richter, J. Am. Chem. Soc. 1998, 120, 9965 – 9966. D. T. Richter, T. D. Lash, J. Org. Chem. 2004, 69, 8842 – 8850. a) R. J. P. Corriu, G. Bolin, J. J. E. Moreau, C. Vernhet, J. Chem. Soc. Chem. Commun. 1991, 211 – 213; b) F. H. Carr, R. J. P. Corriu, G. Bolin, J. J. E. Moreau, C. Vernhet, Organometallics 1993, 12, 2478 – 2486. G. R. Peterson, N. Bampos, Angew. Chem. 2010, 122, 4022 – 4025; Angew. Chem. Int. Ed. 2010, 49, 3930 – 3933. S. Saito, A. Osuka, Angew. Chem. 2011, 123, 4432 – 4464; Angew. Chem. Int. Ed. 2011, 50, 4342 – 4373. A. Osuka, S. Saito, Chem. Commun. 2011, 47, 4330 – 4339. M. G. P. M. S. Neves, R. M. Martins, A. C. Tom, A. J. D. Silvestre, A. M. S. Silva, V. Flix, M. G. B. Drew, J. A. S. Cavaleiro, Chem. Commun. 1999, 385 – 386; J.-Y. Shin, H. Furuta, K. Yoza, S. Igarashi, A. Osuka, J. Am. Chem. Soc. 2001, 123, 7190 – 7191. S. Mori, A. Osuka, J. Am. Chem. Soc. 2005, 127, 8030. S. Mori, A. Osuka, Inorg. Chem. 2008, 47, 3937 – 3939. K. Naoda, H. Mori, A. Osuka, Chem. Asian J. 2013, 8, 1395 – 1398. S. Mori, K. S. Kim, Z. S. Yoon, S. B. Noh, D. Kim, A. Osuka, J. Am. Chem. Soc. 2007, 129, 11344 – 11345. S. Mori, S. Shimizu, R. Taniguchi, A. Osuka, Inorg. Chem. 2005, 44, 4127 – 4129. T. Tanaka, T. Sugita, S. Saito, A. Osuka, Angew. Chem. 2010, 122, 6769 – 6771; Angew. Chem. Int. Ed. 2010, 49, 6619 – 6621. M. Inoue, A. Osuka, Angew. Chem. 2010, 122, 9678 – 9681; Angew. Chem. Int. Ed. 2010, 49, 9488 – 9491. T. Tanaka, A. Osuka, Chem. Eur. J. 2013, 19, 7314 – 7318. S. Gokulnath, K. Yamaguchi, M. Toganoh, S. Mori, H. Uno, H. Furuta, Angew. Chem. 2011, 123, 2350 – 2354; Angew. Chem. Int. Ed. 2011, 50, 2302 – 2306. Y. Tanaka, S. Saito, S. Mori, N. Aratani, H. Shinokubo, N. Shibata, Y. Higuchi, Z. S. Yoon, K. S. Kim, S. B. Noh, J. K. Park, D. Kim, A. Osuka, Angew. Chem. 2008, 120, 693 – 696; Angew. Chem. Int. Ed. 2008, 47, 681 – 684. K. B. Fields, J. T. Engle, S. Sripothongnak, C. Kim, X. P. Zhang, C. J. Ziegler, Chem. Commun. 2011, 47, 749 – 751.

Received: November 30, 2013 Published online: January 31, 2014

705

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim