DOI: 10.1002/chem.201501535

Full Paper

& Metal-Free Hydroamination

Stoichiometric and Catalytic Inter- and Intramolecular Hydroamination of Terminal Alkynes by Frustrated Lewis Pairs Tayseer Mahdi and Douglas W. Stephan*[a] Abstract: Frustrated Lewis pairs (FLPs) based on sterically encumbered anilines and the Lewis acid B(C6F5)3 were found to react with terminal alkynes effecting intermolecular hydroamination affording iminium alkynylborate species of the form [RPhN=C(R’)Me][R’CCB(C6F5)3]. In these cases, the reagent ratio of borane, aniline, and alkyne is 1:1:2. These reac-

tions could also be performed in an intramolecular fashion by using anilines with alkynyl substituents effecting cyclization reactions. The use of 10 mol % B(C6F5)3 under a H2 atmosphere provides a one-pot synthesis of the pyrrolidine 12, the piperidines 13–15, the azepane 16, the isoindoline 17, and the benzoxazine 18.

Introduction Research devoted to metal-free stoichiometric and catalytic transformations exploiting the chemistry of frustrated Lewis pairs (FLPs), that is, the combination of bulky Lewis acids and bases, has become the focus for a number of research groups worldwide. Several recent reviews of these efforts have appeared.[1] Initial studies focused on the ability of FLPs to capture and activate a variety of small molecules including dihydrogen,[1a, 2] alkenes,[3] alkynes,[4] disulphides,[5] CO,[6] CO2,[7] NO,[8] N2O,[9] and SO2.[10] FLPs have also been exploited in radical polymerizations,[8] and more recently, in materials and surface science.[11] Efforts have also continued to exploit FLP chemistry in synthetic organic applications. The majority of these efforts have focused on hydrogenation catalysis with particular noteworthy developments in catalytic hydrogenations, aromatic reductions,[2i,j] stereoselective hydrogenation of N-substrates[12] and alkynes.[13] The reactions of FLPs with alkynes were described shortly after the discovery of FLP chemistry.[4] Initial studies showed that FLPs react with terminal alkynes to effect either deprotonation or addition of the phosphine/Lewis acid combination (Scheme 1 a). The course of the reaction is correlated with the basicity of the phosphine donor. In related work, Berke et al. demonstrated that N-bases resulted in deprotonation of alkynes affording ammonium alkynylborate salts.[14] Alternatively, sulphur/borane FLPs were also found to add to alkynes,[4a, 15] whereas addition of ethylene-linked S/B systems to alkynes

[a] T. Mahdi, Prof. Dr. D. W. Stephan Department of Chemistry University of Toronto 80 St. George St, Toronto ON, M5S 2H6 (Canada) E-mail: [email protected] Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201501535. Chem. Eur. J. 2015, 21, 11134 – 11142

Scheme 1. Examples of FLP reactivity with alkynes. Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl.

were shown to undergo subsequent elimination of ethylene, affording a route to reactive olefin-linked FLPs (Scheme 1 b).[16] Beyond this main-group chemistry, the FLP paradigm has been applied to transition-metal systems in combination with alkynes, affording routes to cationic zirconocene phosphinoaryloxide-hydride complexes through selective deprotonation of terminal alkynes (Scheme 1 c).[17] In a recent paper, we have shown that Ru-acetylides act as carbon nucleophiles in combination with Lewis acids to effect FLP addition to alkynes yielding trans-addition products.[18]

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Full Paper It is also important to note that the groups of Berke and Erker studied the reactivity of Lewis acids and alkynes in the absence of a Lewis base. These groups described 1,1-carboboration reactions that generate alkenylboranes that proceed through nucleophilic addition of the alkyne reagent to the electrophilic borane RB(C6F5)3, followed by migration of a borane substituent to the alkyne carbon.[14, 19] In recent results, novel boron allylation reagents have been generated from alkyne activation of propargyl esters by B(C6F5)3.[20] Efforts to exploit related reactions of Lewis acids and alkynes for organic applications have a long history. More recently, alkynes in the presence of B(C6F5)3 have been shown to undergo both hydrostannation[21] and hydrogermylation[22] reactions. We reported the intramolecular cyclization of an aniline and N-heterocycles with pendant alkyne substituents in combination with B(C6F5)3, thus exploiting FLP addition reactions (Schemes 1 d and e).[23] We have also recently described a catalytic approach to the hydroamination of terminal alkynes yielding enamines. These species could be subsequently hydrogenated to the corresponding amines in a one-pot procedure.[24] Building on these previous results, in this paper we focus our attention on stoichiometric intermolecular hydroamination reactions exploring the amine and alkyne versatility. In addition, we probe related systems to accomplish stoichiometric and catalytic intramolecular hydroamination, an FLP strategy to cyclic amines.

Table 1. Intermolecular hydroamination of terminal alkynes. Entry Amine Alkyne

88 91

82 90

2

(5)

56[b]

3

(6)

75

4

(7)

78

5

(8)

85

[a] The corresponding anions [RCŽCB(C6F5)3] have been omitted. [b] Remainder: the product consisted of 1,1-carboboration of phenylacetylene. The major isomer is depicted.

Stoichiometric intermolecular hydroamination The three component stoichiometric reaction of iPrPhNH, B(C6F5)3, and two equivalents of phenylacetylene in CD2Cl2 resulted in the immediate formation of a bright yellow solution. The isolated product [iPrPhN=C(CH3)Ph][PhCŽCB(C6F5)3] (1) resulting from the sequential hydroamination and deprotonation of phenylacetylene was obtained in 88 % yield (Table 1, entry 1). The new species displayed a diagnostic singlet at d = 2.44 ppm in the 1H NMR spectrum, which is consistent with the CH3 group, in addition to a downfield 13C{1H} NMR resonance at d = 191 ppm attributable to the N=C moeity of the iminium cation. The anionic fragment [PhCŽCB(C6F5)3] gave rise to a singlet at d = ¢20.9 ppm in the 11B NMR spectrum and three distinct 19F resonances at d = ¢132.7, ¢163.7 , and ¢167.2 ppm. The 1H NMR spectrum showed the cation present as a 7:1 mixture of E and Z isomers. The nature of compound 1 was unambiguously confirmed by X-ray crystallographic characterization (Figure 1 a). To probe the generality of this reaction, the corresponding reactivity of various substituted secondary anilines was explored. In this fashion, the species [RPhN=C(CH3)Ph][PhCŽ CB(C6F5)3] [R = cyclohexyl (Cy) (2), PhCH2 (3), p-OMePh (4)] were isolated in 91, 82, and 90 %, respectively (Table 1, entry 1). The compounds were unambigously identified by 1H, 11B, 13C{1H}, and 19F NMR spectroscopy along with elemental analysis. X-ray www.chemeurj.org

Yield [%] R = iPr (1) R = Cy (2) R= CH2Ph (3) R = pOMePh (4)

1

Results and Discussion

Chem. Eur. J. 2015, 21, 11134 – 11142

Product[a]

crystallography also confirmed the formulations of compounds 2 and 3 (see the Supporting Information). The reaction is thought to proceed through Lewis acid polarization of the alkyne by B(C6F5)3 prompting nucleophilic addition of the aniline, generating a zwitterionic intermediate (Scheme 2). Analogous 1,2-additions to alkynes have been pre-

Scheme 2. Proposed mechanism to the iminium alkynylborate salts.

viously reported for phosphine/borane, thioether/borane,[15] and pyrrole/borane[4c] FLPs. However, in the present study, the arylammonium intermediate provides an acidic proton, which migrates to the carbon atom adjacent to boron yielding an enamine with concurrent release of B(C6F5)3. Subsequent to this hydroamination, the FLP derived from the enamine/borane further reacts with an equivalent of the alkyne affording the isolated iminium alkynylborate salt.

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Figure 1. POV-ray depictions of compounds a) 1, b) 6, c) 7, and d) 8.

Analogous reactions of Ph2NH, B(C6F5)3, and two equivalents of 1-hexyne revealed two competitive reaction pathways. In addition to the previously observed sequential hydroamination/deprotonation, the product of 1,1-carboboration was also observed by NMR spectroscopy. Thus in this case, the hydroamination/deprotonation product [Ph2N=C(CH3)Bu][BuCŽ CB(C6F5)3] (5) was obtained in 56 % yield (Table 1, entry 2). Nonetheless, exposing the same aniline/B(C6F5)3 combination to 9-ethynylphenanthrene produced compound [Ph2N= C(CH3)C14H9][C14H9CŽCB(C6F5)3] (6) in 75 % yield (Table 1, entry 3; Figure 1 b). Similarly, the reaction of iPrPhNH/B(C6F5)3 with the sulphur-containing 2-ethynylthiophene proceeded cleanly to give the product [iPrPhN=C(CH3)C4H3S][C4H3SCŽ CB(C6F5)3] (7) obtained in 78 % yield (Table 1, entry 4; Figure 1 c). Interestingly, the stoichiometric combination of Ph2NH, B(C6F5)3 and 1,4-diethynylbenzene resulted in an instant color change from pale orange to deep red affording the zwitterionic product [Ph2N=C(CH3)C6H4CŽCB(C6F5)3] (8) in 85 % yield (Table 1, entry 5; Figure 1 d). Analogous stoichiometric combination of tert-butyl aniline or diisopropylamine and B(C6F5)3 with either one or two equivalents of phenylacetylene resulted in the deprotonation of the terminal alkyne affording the ammonium alkynylborate salt as Chem. Eur. J. 2015, 21, 11134 – 11142

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evidenced by NMR spectroscopy. In these cases, the amine is sufficiently bulky to form an FLP with B(C6F5)3, however, it is also basic to preferentially effect deprotonation of the alkyne. This reaction pathway has been previously observed for basic phosphines and B(C6F5)3 with numerous alkynes.[4a,b] Intramolecular hydroamination The potential of the above-described hydroamination reactions to access N-heterocylces was also probed. To this end, the alkynyl-substituted aniline C6H5NH(CH2)3CŽCH was prepared and exposed to an equivalent of B(C6F5)3 in toluene. 11B NMR spectroscopy indicated the formation of a B–N adduct verified by the resonance at d = ¢2.5 ppm, although heating the reaction mixture for 2 h at 50 8C yielded the cyclized zwitterion C6H5N(CH2)3CCH2B(C6F5)3 (9) isolated as a white solid in 94 % (Scheme 3 a). The 1H NMR spectrum was consistent with the consumption of the NH proton and revealed a diagnostic broad quartet at d = 3.16 ppm with a geminal BH coupling of J = 6.3 Hz indicative of the B(C6F5)3-bound methylene group. A diagnostic sharp singlet at d = ¢13 ppm in the 11B NMR spectrum and the N=C iminium 13C{1H} NMR resonance at d = 200 ppm, in addition to elemental analysis, were consistent

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Full Paper a diagnostic quartet at d = 5.18 ppm, two distinct doublets at d = 4.72 and 4.55 ppm, and an upfield doublet at d = 1.51 ppm assignable to the isoindoline species. The presence of this equilbrium is further supported by the broadened 1H NMR resonance at d = 3.53 ppm corresponding to the [HB(C6F5)3] anion, which is consistent with reversible hydride abstraction from the methine group. In addition, this is further supported by 11B and 19F NMR spectra, which provide evidence of free B(C6F5)3. This hydroamination/hydrogenation protocol was further adapted for catalytic cyclization reactions. In this fashion, C6H5NH(CH2)3CŽCH was treated with 10 mol % of B(C6F5)3 at 80 8C under H2 (4 atm) for 16 h. This gave the desired product 2-methyl-1-phenyl pyrrolidine (12) isolated in 68 % yield (Table 2, entry 1). In a similar fashion the catalytic hydroamina-

Scheme 3. Synthesis of compounds 9–11.

with the formulation of compound 9. The analogous 6-membered ring was prepared from the precursor C6H5NH(CH2)4CŽ CH and an equivlent of B(C6F5)3. In this fashion, the zwitterion C6H5N(CH2)4CCH2B(C6F5)3 (10) was isolated in 99 % yield. The formulation of compound 10 was affirmed by 1H, 11B, 13C{1H}, and 19F NMR data, in addition to elemental analysis (Scheme 3 b). This was unambiguously confirmed by an X-ray crystallographic study (Figure 2).

Table 2. Catalytic intramolecular hydroamination to synthesis compounds 12–19. Entry Amine

Figure 2. POV-ray depiction of compound 10.

Similarly, substituted isoindoline species are accessible from the reaction of the precursor N-(2-ethynylbenzyl)aniline with B(C6F5)3 in toluene. The intramolecular hydroamination proceeded quickly affording a white precipitate in 10 min that was sparingly soluble in toluene. However, upon introduction of H2 (4 atm) and heating at 80 8C for 8 h; the 1H NMR spectrum displayed a quartet at d = 5.56 ppm and a triplet at d = 2.89 ppm that are coupled with a coupling constants of J = 2.6 Hz. The 13C{1H} NMR data showed a resonance at d = 182 ppm. Collectively, these data are consistent with the successive hydroamination and hydrogenation product [2MeC8H6N(Ph)][HB(C6F5)3] (11) isolated in 54 % yield (Scheme 3 c). Although this species is isolated as an insoluble solid from pentane, in CD2Cl2 the [HB(C6F5)3] anion appeared to reversibly deliver hydride to the N=C carbon center generating isoindoline and B(C6F5)3 in about 25 % yield. This was evidenced by Chem. Eur. J. 2015, 21, 11134 – 11142

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BðC F Þ ð10 mol %Þ

6 5 3 °°°°°°°°°°! H2 ð4 atmÞ, 16 h, 80 ‘ C

Product

Yield [%]

1

(12)

68

2

(13)

66

3

(14)

52

4

(15)

72

5

(16)

73

6

(17)

70

7

(18)

89

R=H R = Me

– –

8

tion/hydrogenation of C6H5NH(CH2)4CŽCH gave 2-methyl-1phenylpiperidine (13) in 66 % isolated yield, whereas similar treatment of the para-methoxy- and para-fluoro-substituted aniline rings gave the products 14 and 15 in 52 and 72 %, respectively (Table 2, entries 2–4). Furthermore, cyclization of C6H5NH(CH2)5CŽCH gave the seven-membered heterocycle 2methyl-1-phenylazepane (16) in 73 % yield (Table 2, entry 5).

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Full Paper This reactivity was further extended to the synthesis of bicyclic structures consisting of a benzene ring fused to a five- or six-membered nitrogen-containing ring. To this end, treatment of N-(2-ethynylbenzyl)aniline with 10 mol % B(C6F5)3 at 80 8C under H2 pressure gave the isoindoline product 1-methyl-2phenylisoindoline (17) in 70 % yield (Table 2, entry 6), whereas the catalytic hydroamination/hydrogenation of N-benzyl-2(prop-2-yn-1-yloxy)aniline cleanly gave the cyclized benzoxazine product 18 in 89 % yield (Table 2, entry 7). Interestingly, the cyclization of N-propynyl-substituted anilines was not achieved (Table 2, entry 8). The above-described results illustrate the direct addition of N¢H bonds across alkynes providing an atom-economic route to valuable nitrogen-containing molecules in both stoichiometric and catalytic fashions. Generally, in the literature, hydroamination of alkynes have been achieved by early-transition-metal catalysts[25] although rare-earth,[26] late-transition-metal,[27] and actinide[28] catalysts have also been probed. Other catalytic approaches have involved the use of Brønsted acid[29] or base[30] catalysts. More recently, a highly creative metal-free approach has been developed by Beauchemin et al. in which inter- and intramolecular hydroamination reactions[31] have been exploited. The present results further provide a metal-free approach based on the reactivity of aniline/borane FLP additions to alkynes.

Conclusions In summary, a series of iminium alkynylborate complexes are formed through a consecutive intermolecular hydroamination and deprotonation reaction of aniline/borane FLPs with terminal alkynes. Further expansion of the reactivity led to intramolecular reactions that can be exploited in a catalytic fashion by using a catalytic amount of the Lewis acid B(C6F5)3 and by performing these reactions under a H2 atmosphere. In this fashion intramolecular hydroamination and consecutive hydrogenation affords a one-pot strategy to N-heterocycles. The potential of these new metal-free protocols as a synthetic route to chemicals of pharmaceutical and industrial interest is the subject of on-going study in our laboratories.

Experimental Section General: All preparations were performed under an atmosphere of dry, oxygen-free N2 by means of both standard Schlenk line or glovebox techniques (MBraun glovebox equipped with a ¢35 8C freezer). Pentane and toluene (Aldrich) were dried employing a Grubbstype column system (Innovative Technology), degassed, and stored over molecular sieves (4 æ) in the glovebox. Molecular sieves (4 æ) were purchased from Aldrich Chemical Company and dried at 140 8C under vacuum for 24 h prior to use. [D2]Dichloromethane was purchased from Cambridge Isotope Laboratories, dried over CaH2, and distilled under N2 prior to use. All substituted amines and alkynes were purchased from Sigma–Aldrich or Alfa Aesar. The oils were distilled over CaH2 and solids were sublimed under high vacuum prior to use. B(C6F5)3 was purchased from Boulder Scientific and sublimed at 80 8C under high vacuum before use. Nuclear magnetic resonance spectra were recorded on a Bruker AvanceIII Chem. Eur. J. 2015, 21, 11134 – 11142

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400 MHz or a Varian 400 MHz spectrometer equipped with an HFX AutoX triple resonance indirect probe (used for 13C{1H, 19F} NMR experiments) and spectra were referenced to residual solvent of CD2Cl2 (d(1H) = 5.32 ppm; d(13C) = 53.84 ppm) or externally (11B: (Et2O)BF3, 19F: CFCl3). Chemical Shifts (d) are reported in [ppm] and the absolute values of the coupling constants (Js) are given in [Hz]. NMR assignments are supported by additional 2D and DEPT-135 experiments. Elemental analyses (C, H, N) were performed inhouse, employing a Perkin–Elmer 2400 SeriesII CHNS Analyzer. H2 (grade 5.0) was purchased from Linde and dried through a Nanochem Weldassure purifier column prior to use. Synthesis of E-[Ph(Me)C=N(iPr)Ph][PhCŽCB(C6F5)3] (1), E[Ph(Me)C=N(Cy)Ph][PhCŽCB(C6F5)3] (2), E-[Ph(Me)C=N(CH2Ph)Ph] [PhCŽCB(C6F5)3] (3), and [Ph(Me)C=N(p-C6H4OMe)Ph][PhCŽ CB(C6F5)3] (4): These compounds were prepared in a similar fashion, thus only one preparation is detailed. In a glovebox, a four dram vial equipped with a stir bar was charged with a solution of B(C6F5)3 (0.379 g, 0.740 mmol) and the respective amine (0.740 mmol). To the vial, phenylacetylene (151 mg, 1.48 mmol) was added dropwise over 1 min. Workup 1 (pentane as solvent): The solvent was decanted and the product was washed with pentane (3 Õ 5 mL) to yield the product. Workup 2 (toluene or dichloromethane as solvent): The solvent was removed under reduced pressure and the crude product was washed with pentane to yield the product as a solid. Compound 1: N-Isopropylaniline (100 mg, 0.740 mmol), pentane (10 mL), reaction time 1 h, pale yellow solid, 88 % yield. Crystals suitable for X-ray diffraction were grown from a layered solution of bromobenzene/pentane at ¢35 8C over 16 h. E-[Ph(Me)C=N(iPr)Ph] [PhCŽCB(C6F5)3]: 1H NMR (400 MHz, CD2Cl2): d = 7.73 (tm, 3J(H,H) = 7.7 Hz, 1 H; H5), 7.72 (m, 6 H; H4, H9, H10), 7.46 (dm 3J(H,H) = 7.7 Hz„ 2 H; H3), 7.28 (dm 3J(H,H) = 7.6 Hz„ 2 H; H12), 7.20 (m, 2 H; H8), 7.16 (t 3 J(H,H) = 7.6 Hz„ 2 H; H13), 7.13 (t 3J(H,H) = 7.6 Hz„ 1 H; H14), 4.91 (sept 3J(H,H) = 7.2 Hz„ 1 H; C6), 2.44 (s, 3 H; Me), 1.26 ppm (d 3 J(H,H) = 6.6 Hz„ 6 H; iPr); 19F NMR (377 MHz, CD2Cl2): d = ¢132.7 (m, 2 F; o-C6F5), ¢163.7 (t 3J(F,F) = 20 Hz„ 1 F; p-C6F5), ¢167.2 ppm (m, 2 F; m-C6F5); 11B NMR (128 MHz, CD2Cl2): d = ¢20.9 ppm (s, CB); 13 1 C{ H} NMR (101 MHz, CD2Cl2): d = 191.3 (C1), 148.2 (dm, 1J(C,F) = 236 Hz, CF), 138.1 (dm, 1J(C,F) = 243 Hz, CF), 136.5 (dm, 1J(C,F) = 245 Hz, CF), 134.6 (C2), 133.9 (C5), 131.9 (C10), 131.8 (C7), 131.1 (C12), 131.0 (C4), 130.3 (C9), 127.8 (C13), 127.4 (C11), 125.8 (C14), 125.3 (C3, C8), 93.7 (C15), 61.9 (C6), 28.8 (Me), 20.8 ppm (iPr) (not observed: CŽ CB(C6F5)3, ipso-C6F5); elemental analysis calcd (%) for C43H25BF15N: C 60.66, H 2.96, N 1.65; found: C 60.37, H 3.17, N 1.73. Compound 2: N-Cyclohexylaniline (135 mg, 0.740 mmol), pentane (10 mL), reaction time 1 h, off-white solid, 91 % yield. Crystals suitable for X-ray diffraction were grown from a layered solution of bromobenzene/pentane at ¢35 8C over 16 h. (E/Z ratio = 7:1). E[Ph(Me)C=N(Cy)Ph][PhCŽCB(C6F5)3]: 1H NMR (400 MHz, CD2Cl2): d = 7.69 (tt, 3J(H,H) = 7.4, 4J(H,H) = 2.4 Hz, 1 H; H5), 7.62 (m, 5 H; H4, H12, H13), 7.37 (dm, 3J(H,H) = 7.4 Hz, 2 H; H3), 7.20 (dm, 3J(H,H) = 7.7 Hz, 2 H; H15), 7.11 (m, 4 H; H11, H16), 7.03 (tm, 3J(H,H) = 7.7 Hz, 1 H; H17), 4.39 (tt, 3J(H,H) = 11.9, 3J(H,H) = 3.5 Hz, 1 H; H6), 2.35 (s, 3 H; Me), 1.84 (dm, J(H,H) = 11.7 Hz, 1 H; H7), 1.70 (dm, 2J(H,H) = 14.5 Hz, 1 H; H8), 1.45 (dm, 2J(H,H) = 13.2 Hz, 1 H; H9), 1.33 (m, 1 H; H7), 1.04 (pseudo quart of t, J(H,H) = 13.8, 3J(H,H) = 3.7 Hz, 1 H; H8), 0.80 ppm (pseudo quart of t, 2J(H,H) = 13.2, 3J(H,H) = 3.7 Hz, 1 H; H9); 19F NMR (377 MHz, CD2Cl2): d = ¢132.7 (m, 2 F; o-C6F5), ¢163.8 (t, 1 F; 3 J(F,F) = 21 Hz, p-C6F5), ¢167.3 ppm (m, 2 F; m-C6F5); 11B NMR (128 MHz, CD2Cl2): d = ¢20.8 ppm (s, CB); 13C{1H} NMR (101 MHz, CD2Cl2): d = 191.6 (C1), 134.1 (C5), 132.3 (C13), 131.5 (C15), 131.3 (C4), 130.7 (C12), 128.2 (C16), 126.2 (C17), 125.7 (C3), 125.4 (C11), 69.9 (C6), 32.0 (C7), 29.1 (Me), 24.9 (C8), 24.4 ppm (C9) (not observed: C2, C10,

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Full Paper C14, and all carbon atoms for CŽCB(C6F5)3, ipso-C6F5); elemental analysis calcd (%) for C46H29BF15N: C 61.97, H 3.28, N 1.57; found: C 61.58, H 3.54, N 1.53. Compound 3: N-Benzylaniline (135 mg, 0.740 mmol), dichloromethane (10 mL), reaction time 2 h, pale yellow solid, 82 % yield. Crystals suitable for X-ray diffraction were grown from a layered solution of bromobenzene/pentane at ¢35 8C over 16 h. (E/Z ratio = 4:1). E-[Ph(Me)C=N(CH2Ph)Ph][PhCŽCB(C6F5)3]: 1H NMR (600 MHz, CD2Cl2): d = 7.82 (t, 3J(H,H) = 7.3 Hz, 1 H; H5), 7.77 (t, 3J(H,H) = 7.3 Hz, 2 H; H4), 7.64 (d, 3J(H,H) = 7.3 Hz, 2 H; H3), 7.60 (t, 3J(H,H) = 7.6 Hz, 1 H; H14), 7.53 (t, 3J(H,H) = 7.6 Hz, 2 H; H13), 7.38 (m, 1 H; H10), 7.28 (m, 4 H; H9, H16), 7.16 (t, 3J(H,H) = 7.3 Hz, 2 H; H17), 7.10 (t, 3J(H,H) = 7.3 Hz, 1 H; H18), 6.99 (d, 3J(H,H) = 7.6 Hz, 2 H; H12), 6.79 (d, 3J(H,H) = 7.6 Hz, 2 H; H8), 5.26 (s, 2 H; H6), 2.59 ppm (s, 3 H; Me); 19F NMR (377 MHz, CD2Cl2): d = ¢132.6 (m, 2 F; o-C6F5), ¢163.5 (t, 3J(F,F) = 20 Hz, 1 F; p-C6F5), ¢167.1 ppm (m, 2 F; m-C6F5); 11B NMR (128 MHz, CD2Cl2): d = ¢20.7 ppm (s, CB); 13C{1H} NMR (151 MHz, CD2Cl2): d = 191.2 (C1), 138.6 (C7), 134.2 (C5), 133.9 (C2), 131.7 (C11, C14), 131.1 (C9), 130.9 (C13, C15), 130.4 (C4, C10), 129.6 (C8), 129.4 (C16), 127.8 (C17), 126.3 (C3), 125.8 (C18), 124.1 (C8), 93.8 (C19), 64.5 (C6), 28.6 ppm (Me) (not observed: CŽCB(C6F5)3 and all carbon atoms of B(C6F5)3); elemental analysis calcd (%) for C47H25BF15N: C 62.76, H 2.80, N 1.56; found: C 62.59, H 2.96, N 1.71. Compound 4: (p-C6H4OMe)PhNH (147 mg, 0.740 mmol), pentane (15 mL), room temperature, reaction time 3 h, yellow solid, 73 % yield. (E/Z ratio = 1:1). Z-[Ph(Me)C=N(p-C6H4OMe)Ph][PhCŽCB(C6F5)3 : 1 H NMR (500 MHz, CD2Cl2): d = 7.56 (m, 2 H; H7), 7.48 (m, 1 H; H5), 7.35 (m, 2 H; H3), 7.30 (m, 2 H; H4), 7.26 (m, 2 H; H8), 7.17 (m, 4 H; H12, H15), 7.07 (tm, 3J(H,H) = 7.2 Hz, 2 H; H16), 7.02 (m, 1 H; H17), 6.96 (m, 1 H; H9), 6.88 (dm, 3J(H,H) = 8.7 Hz, 2 H; H11), 6.70 (dm, 3J(H,H) = 8.7 Hz, 2 H; H12), 3.65 (s, 3 H; OMe), 2.73 ppm (s, 3 H; Me); 19F NMR (377 MHz, CD2Cl2): d = ¢132.7 (m, 2 F; o-C6F5), ¢163.7 (t, 1 F; 3 J(F,F) = 21 Hz, p-C6F5), ¢167.2 ppm (m, 2 F; m-C6F5); 11B NMR (128 MHz, CD2Cl2): d = ¢20.8 ppm (s, CB); 13C{1H} NMR (125 MHz, CD2Cl2): d = 188.4 (C1), 161.3 (C13), 148.1 (dm, 1J(C,F) = 241 Hz, CF), 142.1 (C6), 138.1 (dm, 1J(C,F) = 244 Hz, CF), 136.4 1 (dm, 1J(C,F) = 246 Hz, CF), 135.6 (C10), 134.8 (C5), 132.5 (C2), 131.3 (C7), 131.0 (C15), 130.5(C8), 129.7 (C4), 129.2 (C3), 127.8 (C16), 127.4 (C14), 126.9 (C11), 125.7 (C17), 125.5 (C9), 115.5 (C12), 93.7 (C18), 55.7 (OMe), 28.3 ppm 1 (Me); E-[Ph(Me)C=N(p-C6H4OMe)Ph][PhCŽCB(C6F5)3 : H NMR (500 MHz, CD2Cl2): d = 7.56 (m, 2 H; H7), 7.50 (m, 1 H; H5), 7.35 (m, 2 H; H4), 7.30 (m, 2 H; H3), 7.26 (m, 2 H; H8), 7.17 (m, 2 H; H12), 7.02 (m, 2 H; H11), 6.96 (m, 1 H; H9), 3.78 (s, 3 H; OMe), 2.79 ppm (s, 3 H; Me); 13C{1H} NMR (125 MHz, CD2Cl2): d = 189.2 (C1), 162.0 (C13), 143.2 (C6), 134.8 (C5), 134.5 (C10), 132.5 (C2), 131.9 (C7), 131.0 (C3), 129.7 (C4), 125.7 (C11), 125.5 (C9), 124.2 (C8), 116.2 (C12), 55.7 (OMe), 28.3 ppm (Me); elemental analysis calcd (%) for C47H25BF15NO: C 61.66, H 2.75, N 1.53 found: C 61.06, H 2.62, N 1.42 Synthesis of [Bu(Me)C=NPh2][BuCŽCB(C6F5)3] (5), [C14H9(Me)C= NPh2] [C14H9CŽCB(C6F5)3] (6), E-[C4H3S(Me)C=N(iPr)Ph][C4H3SCŽ CB(C6F5)3] (7), and [(C6F5)3BCŽC(C6H4)C(Me) = NPh2] (8): These compounds were prepared in a similar fashion, thus only one preparation is detailed. In the glovebox, a four dram vial equipped with a stir bar was charged with a solution of B(C6F5)3 (0.379 g, 0.740 mmol) and diphenylamine (125 mg, 0.740 mmol). To the vial, the respective alkyne was added over 1 min. Workup 1 (pentane as solvent): The solvent was decanted and the product was washed with pentane (3 Õ 5 mL) to yield the product. Workup 2 (toluene or dichloromethane as solvent): The solvent was removed under reduced pressure and the crude product was washed with pentane to yield the product as a solid. Compound 5: 1-Hexyne (122 mg, 1.48 mmol), pentane (20 mL), ¢35 8C to room temperature, reaction time 2 h, yellow solid, 56 % Chem. Eur. J. 2015, 21, 11134 – 11142

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yield. The reaction also yielded the 1,1-carboboration product that was separated from the reaction mixture through the pentane washing during the workup. 1H NMR (400 MHz, CD2Cl2): d = 7.68 (m, 6 H; Ph), 7.38 (m, 4 H; Ph), 2.82 (m, 2 H; H2), 2.62 (s, 3 H; Me), 2.11 (t, 3J(H,H) = 6.7 Hz, 2 H; H7), 1.80 (quint of t, 3J(H,H) = 7.7, 4 J(H,H) = 2.8 Hz, 2 H; H3), 1.41 (m, 6 H; H4, H8, H9), 0.92 (t, 3J(H,H) = 7.3 Hz, 3 H; H5), 0.87 ppm (t, 3J(H,H) = 7.2 Hz, 3 H; H10); 19F NMR (377 MHz, CD2Cl2): d = ¢132.7 (m, 2 F; o-C6F5), ¢164.3 (t, 3J(F,F) = 21 Hz, 1 F; p-C6F5), ¢167.5 ppm (m, 2 F; m-C6F5); 11B NMR (128 MHz, CD2Cl2): d = ¢21.1 ppm (s, CB), 13C{1H} NMR (101 MHz, CD2Cl2): d = 199.2 (C1), 148.2 (dm, 1J(C,F) = 237 Hz, CF), 141.1 (ipso-Ph), 140.7 (ipso-Ph), 138.2 (dm, 1J(C,F) = 242 Hz, CF), 136.3 (dm, 1J(C,F) = 246 Hz, CF), 131.9 (Ph), 131.5 (Ph), 131.4 (Ph), 123.6 (Ph), 123.4 (Ph), 93.2 (C6), 38.9 (C2), 32.0 (C8), 29.5 (C3), 24.8 (Me), 22.7 (C4), 21.9 (C9), 19.9 (C7), 13.5 (C10), 13.0 ppm (C5) (not observed: CŽCB(C6F5)3, ipsoC6F5); elemental analysis calcd (%) for C42H31BF15N: C 59.66, H 3.70, N 1.66; found: C 58.85, H 3.66, N 1.54. Compound 6: 9-Ethynylphenanthrene (299 mg, 1.48 mmol), pentane (15 mL), room temperature, reaction time 3 h, pale yellow solid, 75 % yield. Crystals suitable for X-ray diffraction were grown from a layered solution of bromobenzene/pentane at ¢35 8C over 16 h. 1H NMR (500 MHz, CD2Cl2): d = 8.59 (dm, 3J(H,H) = 8.2 Hz, 1 H; Ar H), 8.53 (dm, 3J(H,H) = 8.2 Hz, 1 H; ArH), 8.49 (m, 2 H; ArH), 8.45 (dm, 3 J(H,H) = 8.2 Hz, 1 H; ArH), 7.76 (dm, 3J(H,H) = 7.6 Hz, 1 H; ArH), 7.73 (tm, 3J(H,H) = 7.6 Hz, 1 H; ArH), 7.67 (s, 1 H; borateArH), 7.65 (tm, 3 J(H,H) = 8.2 Hz, 1 H; ArH), 7.63 (s, 1 H; amineArH), 7.60 (m, 3J(H,H) = 8.2 Hz, 1 H; ArH), 7.57 (m, 3 H; m,p-Ph), 7.55 (m, 2 H; o-Ph), 7.53 (dm, 3 J(H,H) = 7.6 Hz, 1 H; ArH), 7.48 (m, 2 H; ArH), 7.44 (tm, 3J(H,H) = 7.6 Hz, 1 H; ArH), 7.37 (tm, 3J(H,H) = 7.6 Hz, 1 H; ArH), 7.32 (m, 2 H; Ar H), 7.03 (tt, 3J(H,H) = 7.0, 4J(H,H) = 1.0 Hz, 1 H; ArH), 6.96 (tm, 3 J(H,H) = 7.0 Hz, 2 H; m-Ph), 6.91 (dm, 3J(H,H) = 7.0 Hz, 2 H; o-Ph), 2.84 ppm (Me); 19F NMR (377 MHz, CD2Cl2): d = ¢132.4 (m, 2 F; oC6F5), ¢163.6 (t, 3J(F,F) = 21 Hz, 1 F; p-C6F5), ¢167.1 ppm (m, 2 F; mC6F5); 11B NMR (128 MHz, CD2Cl2): d = ¢20.6 ppm (s, CB); 13 1 C{ H} NMR (125 MHz, CD2Cl2): d = 194.3 (C=N), 150.0 (dm, 1J(C,F) = 242, CF), 144.4 (ipso-Ph), 143.0 (ipso-Ph), 140.0 (dm, 1J(C,F) = 245, CF), 138.6 (dm, 1J(C,F) = 250, CF), 134.2 (ArC), 134.2 (m-Ph), 133.7 (pPh), 133.6 (ArC), 133.4 (o-Ph), 133.0 (p-Ph), 132.6 (ArC), 132.5 (ArC), 132.1 (ArC), 132.0 (m-Ph), 131.9 (ArC), 131.7 (ArC), 131.5 (ArC), 131.3 (ArC), 131.0 (ArC), 130.7 (ArC), 130.6 (ArC), 130.3 (ArC),130.1 (ArC), 129.8 (ArC), 129.7 (ArC), 128.6 (ArC), 128.4 (ArC), 128.4 (ArC), 128.0 (ArC), 127.2 (ArC), 126.1 (o-Ph), 125.0 (o-Ph), 125.9(ArC), 125.9 (ArC), 124.8 (ArC), 124.2 (ArC), 124.1 (ArC), 93.7 (CŽCB), 30.96 ppm (Me); elemental analysis calcd (%) for C62H31BF15N: C 68.59, H 2.88, N 1.29; found: C 68.12, H 3.06, N 1.34. Compound 7: 2-Ethynylthiophene (160 mg, 1.48 mmol), dichloromethane (4 mL), and pentane (10 mL), room temperature, reaction time 1 h, pale pink solid, 78 % yield. Crystals suitable for X-ray diffraction were grown from a layered solution of bromobenzene/ pentane at ¢35 8C over 16 h. (E/Z ratio = 7:1). E-[C4H3S(Me)C= N(iPr)Ph][C4H3SCŽCB(C6F5)3]: 1H NMR (400 MHz, C6D5Br): d = 7.38 (d, 3 J(H,H) = 4.5 Hz, 1 H; H3), 7.33 (t, 3J(H,H) = 7.2 Hz, 1 H; H10), 7.31 (d, 3 J(H,H) = 4.5 Hz, 1 H; H5), 7.26 (t, 3J(H,H) = 7.2 Hz, 2 H; H9), 6.93 (d, 3 J(H,H) = 3.8 Hz, 1 H; H12), 6.74 (d, 3J(H,H) = 5.3 Hz, 1 H; H14), 6.67 (t, 3 J(H,H) = 4.5 Hz, 1 H; H4), 6.64 (dd, 3J(H,H) = 5.3, 3J(H,H) = 3.8 Hz, 1 H; H13), 6.60 (d, 3J(H,H) = 7.2 Hz, 2 H; H8), 4.36 (sept, 3J(H,H) = 6.6 Hz, 1 H; H6), 2.56 (s, 3 H; Me), 0.81 ppm (d, 3J(H,H) = 6.6 Hz, 6 H; iPr); 19 F NMR (377 MHz, C6D5Br): d = ¢131.2 (m, 2 F; o-C6F5), ¢161.9 (t, 3 J(F,F) = 21 Hz, 1 F; p-C6F5), ¢165.6 ppm (m, 2 F; m-C6F5); 11B NMR (128 MHz, C6D5Br): d = ¢20.3 ppm (s, CB); 13C{1H} NMR (101 MHz, C6D5Br): d = 172.4 (C1), 148.6 (dm, 1J(C,F) = 240 Hz, CF), 144.6 (C5), 143.8 (C3), 138.4 (dm, 1J(C,F) = 246 Hz, CF), 136.7 (dm, 1J(C,F) = 267 Hz, CF), 134.6 (C7), 133.0 (C2), 132.4 (C10), 131.2 (C9), 129.0 (C12),

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Ó 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper 128.6 (C4), 127.2 (C8), 126.9 (C13), 123.9 (C14), 59.3 (C6), 21.4 (Me), 20.1 ppm (iPr) (not observed: C11, C15, ipso-C6F5, CŽCB(C6F5)3); elemental analysis calcd (%) for C39H21BF15N: C 54.25, H 2.45, N 1.62; found: C 54.15, H 2.59, N 1.68. Compound 8: 1,4-Diethynylbenzene (160 mg, 1.48 mmol), dichloromethane (10 mL), ¢35 8C to room temperature, reaction time 2 h, orange solid, 85 % yield. Crystals suitable for X-ray diffraction were grown from a layered solution of bromobenzene/pentane at ¢35 8C over 16 h. 1H NMR (400 MHz, CD2Cl2): d = 7.60 (m, 3 H; m,pPh), 7.35 (m, 4 H; o,m-Ph), 7.29 (m, 5 H; C6H4, p-Ph), 7.06 (dm, 3 J(H,H) = 7.7 Hz, 2 H; o-Ph), 2.77 ppm (s, 3 H; Me); 19F NMR (377 MHz, CD2Cl2): d = ¢132.9 (m, 2 F; o-C6F5), ¢163.0 (t, 3J(F,F) = 20 Hz, 1 F; p-C6F5), ¢167.0 ppm (m, 2 F; m-C6F5); 11B NMR (128 MHz, CD2Cl2): d = ¢20.9 ppm (s, CB); 13C{1H} NMR (151 MHz, CD2Cl2): d = 187.7 (C=N), 148.2 (dm, 1J(C,F) = 236 Hz, CF), 143.3 (ipso-Ph), 142.5 (ipso-Ph), 138.3 (dm, 1J(C,F) = 243 Hz, CF), 136.5 (dm, 1J(C,F) = 247 Hz, CF), 136.4 (quaternary C for C6H4), 132.2 (C6H4), 131.7 (pPh), 131.4 (m-Ph), 131.1 (p-Ph), 130.8 (m-Ph), 130.2 (C6H4), 128.2 (quaternary C for C6H4), 125.5 (o-Ph), 124.4 (o-Ph), 122.8 (ipso-C6F5), 93.7 (CŽCB(C6F5)3), 27.6 ppm (Me) (not observed: CŽCB(C6F5)3); elemental analysis calcd (%) for C40H17BF15N: C 59.51, H 2.12, N 1.73; found: C 55.02, H 2.12, N 2.18. Synthesis of C6H5N(CH2)3CCH2B(C6F5)3 (9), C6H5N(CH2)4CCH2B(C6F5)3 (10), and [2-MeC8H6N(Ph)][HB(C6F5)3] (11): These compounds were prepared in a similar fashion, thus only one preparation is detailed. In the glovebox, a 25 mL Schlenk flask equipped with a stir bar was charged with a solution of B(C6F5)3 (0.100 g, 0.195 mmol) in toluene (5 mL) and the alkynyl aniline (0.19 mmol). The solution was heated for 2 h at 50 8C and the solvent was subsequently removed under reduced pressure. The crude oil was washed with pentane (2 Õ 5 mL) to yield the product as a white solid. Compound 9: N-(Pent-4-ynyl)aniline (30 mg, 0.19 mmol), 94 % yield. 1 H NMR (400 MHz, CD2Cl2): d = 7.46 (m, 3 H; m,p-Ph), 6.91 (dm, 3 J(H,H) = 8.6 Hz, 2 H; o-Ph), 4.16 (t, 3J(H,H) = 7.8 Hz, 2 H; H3), 3.33 (br q, 2J(B,H) = 5.4 Hz, 2 H; CH2B), 3.11 (t, 3J(H,H) = 7.8 Hz, 2 H; H1), 2.15 ppm (p, 3J(H,H) = 7.8 Hz, 2 H; H2); 19F NMR (377 MHz, CD2Cl2): d = ¢132.5 (m, 2 F; o-C6F5), ¢160.1 (t, 3J(F,F) = 21 Hz, 1 F; p-C6F5), ¢165.5 ppm (m, 2 F; m-C6F5); 11B NMR (128 MHz, CD2Cl2): d = ¢13.4 ppm (s, CB); 13C{1H} NMR (151 MHz, CD2Cl2): d = 194.2 (C=N), 147.6 (dm, 1J(C,F) = 241 Hz, CF), 139.2 (dm, 1J(C,F) = 243 Hz, CF), 136.6 (dm, 1J(C,F) = 247 Hz, CF), 134.8 (ipso-Ph), 132.4 (p-Ph), 131.1 (m-Ph), 123.1 (o-Ph), 118.9 (ipso-C6F5), 65.1 (C3), 41.1 (C1), 18.5 ppm (CH2B, C2); elemental analysis calcd (%) for C29H13BF15N: C 51.89, H 1.95, N 2.09; found: C 51.40, H 2.19, N 1.91. Compound 10: N-(Hex-5-ynyl)aniline (34 mg, 0.19 mmol), 99 % yield. Crystals suitable for X-ray diffraction were grown from a layered solution of bromobenzene/pentane at ¢35 8C over 16 h. 1H NMR (600 MHz, CD2Cl2): d = 7.45 (tt, 3J(H,H) = 7.5, 4J(H,H) = 2.2 Hz, 1 H; pPh), 7.40 (tm, 3J(H,H) = 7.5 Hz, 2 H; m-Ph), 6.63 (dm, 3J(H,H) = 7.5 Hz, 2 H; o-Ph), 3.72 (t, 3J(H,H) = 7.3 Hz, 2 H; H4), 3.16 (br q, 2J(B,H) = 6.3 Hz, 2 H; CH2B), 2.75 (t, 3J(H,H) = 7.3 Hz, 2 H; H1), 1.97 (m, 2 H; H3), 1.76 ppm (m, 2 H; H2); 19F NMR (377 MHz, CD2Cl2): d = ¢132.0 (m, 2 F; o-C6F5), ¢161.1 (t, 3J(F,F) = 20 Hz, 1 F; p-C6F5), ¢165.6 ppm (m, 2 F; m-C6F5); 11B NMR (128 MHz, CD2Cl2): d = ¢13.0 ppm (s, CB); 13 1 C{ H} NMR (151 MHz, CD2Cl2): d = 200.5 (C=N), 148.1 (dm, 1J(C,F) = 241 Hz, CF), 142.0 (ipso-Ph), 138.4 (dm, 1J(C,F) = 243 Hz, CF), 136.6 (dm, 1J(C,F) = 247 Hz, CF), 130.1 (m,p-Ph), 122.6 (ipso-C6F5), 123.7 (oPh), 57.4 (C4), 38.0 (CH2B), 32.6 (C1), 21.3 (C3), 17.5 ppm (C2); elemental analysis calcd (%) for C30H15BF15N: C 52.28, H 2.21, N 2.04; found: C 52.06, H 2.72, N 1.77. Compound 11: N-(2-Ethynylbenzyl)aniline (39 mg, 0.19 mmol), 54 % yield. 1H NMR (600 MHz, CD2Cl2): d = 8.12 (d of pseudo t, 3J(H,H) = Chem. Eur. J. 2015, 21, 11134 – 11142

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7.9, J(H,H) = 1.0 Hz, 1 H; H9), 7.99 (td, 3J(H,H) = 7.9, 4J(H,H) = 1.0 Hz, 1 H; H8), 7.86 (dm, 3J(H,H) = 7.9 Hz, 1 H; H6), 7.82 (td, 3J(H,H) = 7.9, 4 J(H,H) = 1.0 Hz, 1 H; H7), 7.73–7.69 (m, 3 H; H2, H3), 7.45 (dm, 3 J(H,H) = 7.6 Hz, H1), 5.56 (q, J(H,H) = 2.6 Hz, 2 H; H4), 3.53 (br s, 1 H; HB), 2.89 ppm (t, J(H,H) = 2.6 Hz, Me); 19F NMR (564 MHz, CD2Cl2): d = ¢134.1 (br s, 2 F; o-C6F5), ¢164.4 (br s, 1 F; p-C6F5), ¢167.4 ppm (br s, 2 F; m-C6F5); 11B{1H} NMR (192 MHz, CD2Cl2): d = ¢25.2 ppm (s, HB); 13C{1H} NMR (151 MHz, CD2Cl2): d = 182.0 (N=C), 148.0 (dm, 1 J(C,F) = 247 Hz, CF), 143.7 (C10), 137.3 (C7), 136.6 (dm, 1J(C,F) = 241 Hz, CF), 136.2 (dm, 1J(C,F) = 241 Hz, CF), 134.7 (ipso-Ph), 133.7 (C5), 132.2 (C3), 130.8 (C2), 130.6 (C8), 126.6 (C9), 124.7 (C1), 123.4 (C6), 65.7 (C4), 14.9 ppm (Me) (not observed: ipso-C6F5); elemental analysis calcd (%) for C33H15BF15N: C 54.95, H 2.10, N 1.94; found: C 55.02, H 2.12, N 2.18. Catalytic Synthesis of 2-MeC4H7N(Ph) (12), 2-MeC5H9N(Ph) (13), 2-MeC5H9N(p-CH3OC6H4) (14), 2-MeC5H9N(p-FC6H4) (15), 2MeC6H11N(Ph) (16), C9H10N(CH2Ph) (17), 2-MeC8H7N(Ph) (18), and C9H10N(CH2Ph)O (19): These compounds were prepared in a similar fashion, thus only one preparation is detailed. In the glovebox, a 25 mL Schlenk bomb equipped with a stir bar was charged with a solution of B(C6F5)3 (20 mg, 0.039 mmol) in toluene (2 mL) and the alkynyl aniline (0.39 mmol). The solution was heated for 16 h at 80 8C and the solvent was subsequently removed under reduced pressure. The crude oil was washed with pentane (2 Õ 5 mL) and purified by column chromatography by using hexane/ethyl acetate (6:1) as eluent. Compound 12: N-(Pent-4-ynyl)aniline (60 mg, 0.39 mmol), 68 % yield. 1H NMR (500 MHz, CD2Cl2): d = 7.18 (t, 3J(H,H) = 7.8 Hz, 2 H; mPh), 6.60 (tt, 3J(H,H) = 7.8, 4J(H,H) = 1.1 H; 1 H; p-Ph), 6.57 (d, 3 J(H,H) = 7.8 Hz, 2 H; o-Ph), 2.86 (h, 3J(H,H) = 6.1 Hz, 1 H; NCHCH3), 2.82 (ddd, 2J(H,H) = 8.8, 3J(H,H) = 7.8, 3.5 Hz, 1 H; H3), 2.54 (pseudo q, 3J(H,H) = 8.3 Hz, 1 H; H3), 2.11–1.62 (m, 4 H; H1, H2),0.99 ppm (d, 3 J(H,H) = 6.1 Hz, 3 H; Me); 13C{1H} NMR (151 MHz, CD2Cl2): d = 147.4 (ipso-Ph), 128.9 (m-Ph), 114.8 (p-Ph), 111.6 ppm (o-Ph); major: d = 54.0 (NCHCH3), 47.8 (C3), 33.0 (C1), 26.5 (C2), 19.7 ppm (Me); HRMS (ESI + ): m/z calcd for C11H16N: 162.12827 [M+ +H] + ; found: 162.12755. Compound 13: N-(Hex-5-ynyl)aniline (68 mg, 0.39 mmol), 66 % yield. H NMR (500 MHz, CD2Cl2): d = 7.23 (t, 3J(H,H) = 8.1 Hz, 2 H; m-Ph), 6.93 (d, 3J(H,H) = 8.1 Hz, 2 H; o-Ph), 6.80 (tt, 3J(H,H) = 8.1, 4J(H,H) = 1.1 H; 1 H; p-Ph), 3.94 (m, 1 H; NCHCH3), 3.23 (dt, 2J(H,H) = 12.1, 3 J(H,H) = 4.4 Hz, 1 H; H4), 2.97 (dm, 2J(H,H) = 12.1 Hz, 1 H; H4), 1.90– 1.60 (m, 6 H; H1, H2, H3), 1.00 ppm (d, 3J(H,H) = 6.72, 3 H; Me); 13 1 C{ H} NMR (151 MHz, CD2Cl2): d = 151.6 (ipso-Ph), 128.8 (m-Ph), 118.7 (p-Ph), 117.3 (o-Ph), 51.2 (NCHCH3), 44.6 (C4), 31.7 (C1), 26.1 (C3), 19.8 (C2), 13.4 ppm (Me); HRMS (ESI + ): m/z calcd for C12H18NO: 176.14392 [M+ +H] + ; found: 176.14338. 1

Compound 14: N-(Hex-5-yn-1-yl)-4-methoxyaniline (79.2 mg, 0.390 mmol), 52 % yield. 1H NMR (500 MHz, C6D5Br): d = 7.12 (d, 3 J(H,H) = 8.5 Hz, 2 H; m-C6H4OCH3), 7.00 (d, 3J(H,H) = 8.5 Hz, 2 H; oC6H4OCH3), 3.74 (s, 3 H; OCH3), 3.49 (m, 1 H; NCHCH3), 3.09 (m, 1 H; H4), 3.02 (m, 1 H; H4), 1.94 (m, 1 H; H1), 1.84 (m, 1 H; H3), 1.78 (m, 1 H; H2), 1.76 (m, 1 H; H3), 1.61 (m, 1 H; H1), 1.58 (m, 1 H; H2), 1.06 ppm (d, 3J(H,H) = 6.5 Hz, 3 H; CH3); 13C{1H} NMR (125 MHz, C6D5Br): d = 154.2 (p-C6H4OCH3), 145.7 (ipso-C6H4OCH3), 122.1 (mC6H4OCH3), 113.9 (o-C6H4OCH3), 54.6 (OCH3), 53.4 (NCHCH3), 49.6 (C4), 33.1 (C1), 26.4 (C3), 21.4 (C2), 16.0 ppm (CH3); HRMS (ESI + ): m/z calcd for C13H19NO: 206.1539 [M+ +H] + ; found: 206.1539. Compound 15: 4-Fluoro-N-(hex-5-yn-1-yl)aniline (74.5 mg, 0.390 mmol), 72 % yield. 1H NMR (400 MHz, C6D5Br): d = 6.52 (t, J(H,H) = 8.8 Hz, 2 H; m-C6H4F), 6.37 (dd, 3J(H,H) = 8.8, 4J(F,H) = 4.8 Hz, 2 H; o-C6H4F), 3.06 (m, 1 H; NCHCH3), 2.41 (m, 1 H; H4), 1.35 (m, 1 H; H1), 1.21 (m, 1 H; H3), 1.13 (m, 2 H; H2,3), 1.02 (m, 1 H; H2), 1.01 (m, 1 H; H2), 0.45 ppm (d, 3J(H,H) = 6.5 Hz, 3 H; CH3); 19F NMR (377 MHz,

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Full Paper C6D5Br): d = ¢123.5 ppm (s, 1 F; C6H4F); 13C{1H} NMR (100 MHz, C6D5Br): d = 158.2 (q, 1J(C,F) = 297.4 Hz, p-C6H4F), 147.9 (ipso-C6H4F), 120.2 (d, 3J(C,F) = 7.7 Hz, o-C6H4F), 115.0 (d, 3J(C,F) = 22.7 Hz, mC6H4F), 51.8 (NCHCH3), 47.0 (C4), 32.1 (C1), 26.0 (C3), 20.3 (C2), 14.6 ppm (CH3); HRMS (ESI + ): m/z calcd for C12H16NF: 194.1340 [M+ +H] + ; found: 194.1337.

ing Information. CCDC-1019975 (1), 1019976 (2), 1019977 (3), 1019978 (6), 1019979 (7), 1019980 (8), and 1019981 (9) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

Compound 16: N-(Hept-6-yn-1-yl)aniline (72.9 mg,0.390 mmol), 73 % yield. 1H NMR (400 MHz, CD2Cl2): d = 7.06 (t, 3J(H,H) = 7.8 Hz, 2 H; mPh), 6.57 (d, 3J(H,H) = 7.8 Hz, 2 H; o-Ph), 6.45 (t, 3J(H,H) = 7.8 Hz, 1 H; p-Ph), 3.64 (dp, 3J(H,H) = 12.2, 6.2 Hz, 1 H; CH), 3.37 (dm, 2J(H,H) = 15.5 Hz, 1 H; NCH2), 3.10 (ddd, 2J(H,H) = 15.5, 3J(H,H) = 11.4, 1.6 Hz, 1 H; NCH2), 2.00 (m, 1 H; CH2), 1.74–1.13 (m, 7 H; CH2), 1.02 ppm (d, 3 J(H,H) = 6.2 Hz, 3 H; CH3); 13C{1H} NMR (125 MHz, CD2Cl2): d = 148.4 (ipso-Ph), 129.1 (m-Ph), 114.1 (p-Ph), 110.2 (o-Ph), 52.5 (CH), 42.3 (NCH2), 37.5 (CH2), 30.0 (CH2), 27.6 (CH2), 25.6 (CH2), 17.5 ppm (CH3); HRMS (DART + ): m/z calcd for C13H19N: 190.15957 [M+ +H] + ; found: 190.15959.

Acknowledgements D.W.S. gratefully acknowledges financial support by the NSERC of Canada and the award of a Canada Research Chair. T.M. is grateful for an NSERC CGS-D award. Keywords: alkynes · anilines · frustrated Lewis pairs · hydroamination · hydrogen activation

Compound 17: N-(2-Ethynylbenzyl)aniline (80.8 mg, 0.390 mmol), 70 % yield. 1H NMR (400 MHz, CD2Cl2): d = 7.78 (d, 3J(H,H) = 7.7 Hz, 1 H; C6H4), 7.45–7.37 (m, 5 H; m-Ph, C6H4), 7.07 (t, 3J(H,H) = 7.7 Hz, 1 H; p-Ph), 7.03 (d, 3J(H,H) = 7.7 Hz, 2 H; o-Ph), 5.10 (q, 3J(H,H) = 6.6 Hz, 1 H; NCH(CH3)), 4.83 (d, 2J(H,H) = 13.8 Hz, 1 H; CH2), 4.63 (d, 2 J(H,H) = 13.8 Hz, 1 H; CH2), 1.54 ppm (d, 3J(H,H) = 6.6 Hz, 3 H; CH3);); 13C{1H} NMR (151 MHz, CD2Cl2): d = 143.5 (ipso-Ph), 137.6 (C1), 134.3 (C6), 129.7 (m-Ph), 128.3 (C3, C4), 124.5 (C2), 122.6 (p-Ph), 122.2 (C5), 116.1 (o-Ph), 64.1 (NCH(CH3)), 56.3 (CH2), 18.2 ppm (CH3); HRMS (DART + ): m/z calcd for C15H15N: 210.12827 [M+ +H] + ; found: 210.12767. Compound 18: N-Benzyl-2-(prop-2-yn-1-yloxy)aniline (92.5 mg, 0.390 mmol), 89 % yield. 1H NMR (400 MHz, CD2Cl2): d = 7.23 (m, 5 H; Ph), 6.68 (dd, 3J(H,H) = 7.8, 4J(H,H) = 1.6 Hz, 1 H; C6H4), 6.62 (td, 3 J(H,H) = 7.8, 4J(H,H) = 1.6 Hz, 1 H; C6H4), 6.47 (td, 3J(H,H) = 7.8, 4 J(H,H) = 1.6 Hz, 1 H; C6H4), 6.41 (dd, 3J(H,H) = 7.8, 4J(H,H) = 1.6 Hz, 1 H; C6H4), 4.43 (d, 2J(H,H) = 16.6 Hz, 1 H; CH2Ph), 4.28 (d, 2J(H,H) = 16.6 Hz, 1 H; CH2Ph), 4.09 (dm, 2J(H,H) = 10.6 Hz, 1 H; OCH2), 3.96 (dm, 2J(H,H) = 10.6 Hz, 1 H; OCH2), 3.43 (qm, 3J(H,H) = 6.4 Hz, 1 H; CH), 1.12 ppm (d, 3J(H,H) = 6.4 Hz, 3 H; CH3); 13C{1H} NMR (100 MHz, CD2Cl2): d = 144.0 (quaternary C for C6H4), 139.5 (ipso-Ph), 135.1 (quaternary C for C6H4), 128.6 (m-Ph), 126.8 (o,p-Ph), 121.3 (C6H4), 116.8 (C6H4), 115.8 (C6H4), 112.7 (C6H4), 69.3 (OCH2), 53.1 (CH2Ph), 51.3 (CH), 15.4 ppm (CH3); HRMS (DART + ): m/z calcd for C16H17NO: 240.13884 [M+ +H] + ; found: 240.13871. X-ray data solution and refinement: Non-hydrogen atomic scattering factors were taken from the literature tabulations.[< 32] The heavy-atom positions were determined by using direct methods employing the SHELX-2013 direct methods routine. The remaining non-hydrogen atoms were located from successive difference Fourier map calculations. The refinements were carried out by using full-matrix least-squares techniques on F, minimizing the function w(Fo¢Fc)2, where the weight w is defined as 4 F 2o/2 s(F 2o) and Fo and Fc are the observed and calculated structure factor amplitudes, respectively. In the final cycles of each refinement, all non-hydrogen atoms were assigned anisotropic temperature factors in the absence of disorder or insufficient data. In the latter cases, atoms were treated isotropically. C¢H atom positions were calculated and allowed to ride on the carbon atom to which they are bonded assuming a C¢H bond length of 0.95 æ. Hydrogen-atom temperature factors were fixed at 1.20 times the isotropic temperature factor of the C atom to which they are bonded. The hydrogen-atom contributions were calculated, but not refined. The locations of the largest peaks in the final difference Fourier map calculation as well as the magnitude of the residual electron densities in each case were of no chemical significance. For more information, see the SupportChem. Eur. J. 2015, 21, 11134 – 11142

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