DOI: 10.1002/chem.201405407

Communication

& Asymmetric Catalysis

Highly Enantioselective [3+2] Cycloaddition of Vinylcyclopropane with Nitroalkenes Catalyzed by Palladium(0) with a Chiral Bis(tert-amine) Ligand Feng Wei,[a, b] Chuan-Li Ren,[a, b] Dong Wang,[a] and Li Liu*[a] Abstract: An enantioselective [3+2] cycloaddition of vinyl cyclopropane derived from 1,3-indanedione with nitroalkenes catalyzed by palladium(0) with a chiral bis(tertamine) ligand was developed in high yields with good diastereoselectivities and excellent enantioselectivities. The resulting bis(tert-amine)–palladium complex proved to be a highly efficient catalyst for this cycloaddition.

Recently, extensive progress has been made on the [3+2] cycloaddition, a powerful tool for constructing five-membered rings with excellent atom-economy and applicability.[1] As precursors of formal 1,3-dipole, donor–acceptor (D–A) cyclopropanes, which have electron-withdrawing groups stabilizing the anion and electron-donating groups stabilizing the cation, have been extensively applied in the [3+2] cycloaddition.[2] Among them, vinylcyclopropanes bearing electron-withdrawing groups can be transformed easily into formal 1,3-dipoles in the presence of low-valent metals, such as Pd,[3] Ni,[4] Fe,[5] and Ir[6] catalyst.[7] Under Pd0 catalysis, vinyl cyclopropanes showed excellent capability in introducing a three-carbon-atom fragment, which subsequently could be easily trapped with olefins[3a, 8] and other dipolarophiles (Scheme 1a).[3b, 9] Trost and coworkers reported the enantioselective [3+2] cycloaddition of vinyl cyclopropanes with alkylidene azlactones and Meldrum’s acid alkylidenes catalyzed by Pd0 with a chiral bis(amide)–P,Pligand, providing the products bearing a cyclopentane unit in good yields with high enantio- and diastereoselectivities.[8b, d] Shi et al. reported the enantioselective reaction of vinylcyclopropanes with b,g-unsaturated a-keto esters and isatin derivatives catalyzed by Pd0 with a chiral binaphthyl-N,P-ligand to afford cyclopentanes and oxaspirooxindoles, respectively.[8c, 9b]

Scheme 1. [3+2] cycloaddition of vinylcyclopropanes with olefins under Pd0 catalysts.

As a useful dipolarophile, nitroalkenes have been widely employed in the reaction with a 1,3-dipole to furnish nitro-groupcontaining five-membered cyclic compounds,[10] which can be readily transformed further. More recently, Stoltz and co-workers reported a [3+2] cycloaddition of vinylcyclopropane with a b-nitrostyrene to rapidly assemble the cyclopentane core of Melodinus alkaloids.[8a] However, an asymmetric transformation of vinylcyclopropanes with nitroalkenes has not been reported yet. 1,3-Indanedione and its derivatives containing spirocyclopentane have attracted great attention due to their utilities for constructing building motifs in biologically active natural compounds, pharmaceutically useful molecules, and functional materials.[11] For example, Fredericamycin A[12] was found to be the most active among several classes of antibiotics isolated from soil bacterium, and indacrinone (MK-196)[13] displayed uricosuric-diuretic activity (Scheme 2). As special donor–acceptor cyclopropanes, in most cases the electron-withdrawing groups of vinylcyclopropanes are ester groups.[2f] To access the structure of 1,3-indanedione bearing

[a] F. Wei, C.-L. Ren, Prof. Dr. D. Wang, Prof. Dr. L. Liu Beijing National Laboratory for Molecular Sciences (BNLMS) CAS Key Laboratory of Molecular Recognition and Function Institute of Chemistry, Chinese Academy of Sciences Beijing 100190 (China) Fax: (+ 86)-10-62554614 E-mail: [email protected] [b] F. Wei, C.-L. Ren University of Chinese Academy of Sciences Beijing 100049 (China) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201405407. Chem. Eur. J. 2014, 20, 1 – 5

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Scheme 2. Examples of biologically active molecules.

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Communication a 2-spirocyclopentane unit, we designed a novel vinylcyTable 1. Screening the chiral ligands for Pd0 catalyst. clopropane as a precursor of a formal 1,3-dipole (Scheme 1b). The product of the [3+2] cycloaddition has both indanedione and cyclopentane moieties, as well as three newly generated chiral centers. Therefore, performing the reaction asymmetrically will be an interesting and challenging task. Herein, we report enantioselective [3+2] cycloaddition reactions of vinylcycloproEntry[a] Ligand Yield d.r[c] ee pane derived from 1,3-indanedione with nitroalkenes [b] [%] [%][d] catalyzed by [Pd2(dba)3] (dba = dibenzylideneacetone) 1 L1 60 3:1 55 with chiral N,N-ligands in good yields with good diaste2 L2 66 1.4:1 0 reoselectivities and excellent enantioselectivities. 3 L3 83 4.7:1 0 Chiral P,P- and N,P-ligands have successfully been ap4 L4 trace – – plied in the enantioselective [3+2] annualtion of vinylcy5 L5 84 10:1 10 6 L6 78 7:1 8 clopropanes with electron-deficient olefins.[8b–d, 9b] Nota7 L7 83 9:1 88 bly, it is usual to employ phosphine-containing chiral li8 L8 30 3:1 9 gands combining with Pd0 catalyst in this type of enan9 L9 50 2.8:1 65 tioselective cycloaddition. To begin our study, the reac10 L10 80 5:1 97 11 L11 n.r. – – tion of indane-1,3-dione-2-spirovinylcyclopropane (1) [e] L10 73 2.8:1 85 12 with nitroalkene (2 a) was performed in the presence of catalyst [Pd2(dba)3] (5 mol %) with a chiral P,P-ligand (L1) [a] The reaction was conducted with 1 (0.1 mmol) and 2 a (0.2 mmol) in THF (0.5 mL) at 40 8C. [b] Isolated yield of diastereoisomers. [c] The diastereomeric (10 mol %) giving product 3 a in 60 % yield with 3:1 d.r. ratios were determined by 1H NMR spectroscopy. [d] The ee values were deterand 55 % ee (Table 1, entry 1 and Figure 1). Then, chiral mined by chiral HPLC analysis. [e] The loading of catalyst is [Pd2(dba)3] (2 mol %) N,P-ligands L2 and L3 were employed under the same with L10 (5 mol %). n.r. = No Reaction. reaction conditions and product 3 a was also obtained, but as a racemic mixture (entries 2–3). Bis(oxazoline) ligand L4 only gave a trace amount of the product (entry 4). However, chiral bis(tert-amine) ligand L5 provided not only good yield but also high diastereoselectivity, although the ee value is 10 % (entry 5). Thus, we turned our attention on the catalytic system of Pd0 with chiral N,N-ligand in the enantioselective [3+2] cycloaddition. Chiral bis(tert-amine)type ligands with relatively strong basicity and coordination ability were employed in this reaction. When the substituents on nitrogen were changed to isoindolin-2-yl (L6), no improvement was made (entry 6). To our delight, when ligand L7 was used, the reaction afforded 3 a in 83 % yield with 9:1 diastereoselectivity and 88 % ee (entry 7). Comparing L7 with L8, the best length of the linker was found to be ethylene (two carbon) (entries 7 vs. 8). For L9, derived from chiral diphenyl ethylenediamine, no improvement was observed (entry 9). However, with L10, the so-called “sterically sym- Figure 1. Chiral ligands for Pd0-catalyzed [3+2] cycloaddition of 1 with 2 a. &

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Communication metric” ligand,[14] the enantiomeric excess of the product 3 a was increased sharply up to 97 % (entry 8). However, L11 derived from (S)-binaphthyl resulted in no reaction that exhibited mismatched double asymmetric inductions (entry 10 vs. 11). The more bulky substitutes on the nitrogen atom of 1,2-cyclohexanediamine exhibited great influence on the enantioselectivity. Solvent effects were also examined and THF was found to be the best solvent (see the Supporting Information). Under the optimized conditions, the substrate scope was subsequently investigated, and the results are summarized in Table 2. In general, with the substituents on the phenyl ring being either electron-donating or -withdrawing groups, the desired products were attained in good yield with moderate diastereoselectivities and excellent ee values (92–99 % ee, entries 1–11). Notably, when the R is o-CF3C6H4, the corresponding adduct 3 d could be obtained in a slightly lower yield with up to 14:1 diastereoselectivity and excellent ee values (entry 4). Moreover, for heteroaromatic rings or fused rings, the corresponding adducts 3 l–o were attained with excellent results (entries 12–15). Meanwhile, when cyclopropyl- and cyclohexylsubstituted nitroalkenes were employed, the reaction also proceeded efficiently to provide adducts 3 p and 3 q in good yields with excellent enantioselectivities (99 % ee) but lower diastereoselectivities (entries 16 and 17). On the basis of these results and previous literature,[3a, 14] a plausible catalytic cycle was proposed in Scheme 3. The vinyl cyclopropane 1 was transformed into a zwitterionic (p-allyl) palladium intermediate A, which can attack the nitroalkene to

Scheme 3. Proposed mechanism.

afford spiro[cyclopentane-1,2’-indene]-1’,3’-dione adducts 3 through intermediate B. The stereoselectivity of the reaction came from the bulky substitutes on the nitrogen atom of ligands. The two naphthyl groups could not co-exist in the same plane due to the existence of the seven-membered ring on the nitrogen atom,[14b] and the axial chirality on the binaphthyl, which would form a C2-symmetric chiral pocket (see the Supporting Information). The desired cycloaddition product 3 could be easily transformed further. When 3 a was treated under reductive conditions of indium powder in AcOH at 50 8C, the crude product 4 obtained was reacted with 5 without purification under the catalysis of Et3N in dry dichloromethane overnight to afford the product 6 in 73 % yield in 5:1 d.r (over two steps) in 97 % ee for the major diastereomer (Scheme 4). The configuration of the newly generated three stereogenic centres were revealed by the single X-ray crystallographic analysis of the crystal of 6.[15] In conclusion, we have developed a bis(tert-amine)–palladium-complex-catalyzed enantioselective [3+2] cycloaddition between indane-1,3-dione-derived vinyl cyclopropanes and nitroalkenes in good yields with good diastereoselectivities and excellent enantioselectivities. This protocol afforded an efficient and convenient approach to the synthesis of spirocyclopentyl indane-1,3-dione derivatives.

Table 2. Substrate scope for Pd0-catalyzed [3+2] cycloaddition.

Entry[a]

Nitroalkene (R)

Product

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

2 a, C6H5 2 b, 4-FC6H4 2 c, 4-BrC6H4 2 d, 2-CF3C6H4 2 e, 2-FC6H4 2 f, 4-MeOC6H4 2 g, 2-F-6-ClC6H3 2 h, 2-MeOC6H4 2 i, 4-MeC6H4 2 j, 2 -BrC6H4 2 k, 4-ClC6H4 2 l, 1-naphthyl 2 m, 2-naphthyl 2 n, 2-thiophene 2 o, 2-furyl 2 p, cyclopropyl 2 q, cyclohexyl

3a 3b 3c 3d 3e 3f 3g 3h 3i 3j 3k 3l 3m 3n 3o 3p 3q

Yield [%][b] 80 87 84 75 82 92 85 90 81 79 90 83 81 80 89 86 88

d.r[c]

ee [%][d]

5:1 5:1 4.4:1 14:1 6.4:1 5.5:1 5.3:1 2.6:1 5:1 4.1:1 5.3:1 2.3:1 5.7:1 6:1 5.7:1 1.7:1 1.2:1

97:95 96:95 92:80 99:55 96:89 98:90 97:90 97:97 96:88 92:84 92:68 97:97 98:80 97:87 96:78 99:99 99:99

Experimental Section A solution of enantiomerically pure ligand L10 (0.01 mmol, 10 mol %) and palladium dibenzylideneacetone ([Pd2(dba)3]) (0.005 mmol, 5 mol %) in THF (0.25 mL) was stirred at 40 8C under an argon atmosphere for 30 min. To the solution was added a solution of vinylcyclopropane (1; 0.1 mmol, 1 equiv) and (E)-b-nitrostyrene (2 a, 0.2 mmol, 2.0 equiv) in THF (0.25 mL), and the reaction was stirred at 40 8C for 36 h. The mixture was concentrated in vacuo to yield the crude product, which was purified by flash chromatography on silica gel (eluent: PE/EtOAc, 6:1 to 10:1) to furnish the desired cyclopentane 3 a as a white solid.

[a] The reaction was conducted with 1 (0.1 mmol) and 2 a–q (0.2 mmol) in THF (0.5 mL) at 40 8C. [b] Isolated yield of diastereoisomer. [c] The diastereomeric ratios were determined by 1H NMR spectroscopy. [d] The ee values were determined by chiral HPLC analysis.

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Scheme 4. Transformation of the product.

Acknowledgements We thank the National Natural Science Foundation of China (Nos. 21372224 and 21232008), Ministry of Science and Technology (2011CB808600) and the Chinese Academy of Sciences for financial support. Keywords: asymmetric catalysis · cycloaddition · nitroalkenes · palladium catalyst · vinylcyclopropane

[11]

[1] a) K. V. Gothelf, K. A. Jørgensen, Chem. Rev. 1998, 98, 863 – 910; b) A. Padwa, W. H. Pearson, Synthetic applications of 1, 3-dipolar cycloaddition chemistry toward heterocycles and natural products, Vol. 59, Wiley, 2003; c) G. Pandey, P. Banerjee, S. R. Gadre, Chem. Rev. 2006, 106, 4484 – 4517; d) N. A. Bokach, M. L. Kuznetsov, V. Y. Kukushkin, Coord. Chem. Rev. 2011, 255, 2946 – 2967; e) S. Yu, S. Ma, Angew. Chem. Int. Ed. 2012, 51, 3074 – 3112; Angew. Chem. 2012, 124, 3128 – 3167. [2] For reviews on donor–acceptor cyclopropanes, see: a) H.-U. Reissig, R. Zimmer, Chem. Rev. 2003, 103, 1151 – 1196; b) M. Yu, B. L. Pagenkopf, Tetrahedron 2005, 61, 321 – 347; c) M. Rubin, M. Rubina, V. Gevorgyan, Chem. Rev. 2007, 107, 3117 – 3179; d) C. A. Carson, M. A. Kerr, Chem. Soc. Rev. 2009, 38, 3051 – 3060; e) S. Liao, X.-L. Sun, Y. Tang, Acc. Chem. Res. 2014, 47, 2260 – 2272; f) T. F. Schneider, J. Kaschel, D. B. Werz, Angew. Chem. Int. Ed. 2014, 53, 5504 – 5523; Angew. Chem. 2014, 126, 5608 – 5628. [3] a) I. Shimizu, Y. Ohashi, J. Tsuji, Tetrahedron Lett. 1985, 26, 3825 – 3828; b) A. T. Parsons, M. J. Campbell, J. S. Johnson, Org. Lett. 2008, 10, 2541 – 2544. [4] a) R. K. Bowman, J. S. Johnson, Org. Lett. 2006, 8, 573 – 576; b) R. Tombe, T. Kurahashi, S. Matsubara, Org. Lett. 2013, 15, 1791 – 1793. [5] A. P. Dieskau, M. S. Holzwarth, B. Plietker, J. Am. Chem. Soc. 2012, 134, 5048 – 5051.

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[6] J. Moran, A. G. Smith, R. M. Carris, J. S. Johnson, M. J. Krische, J. Am. Chem. Soc. 2011, 133, 18618 – 18621. [7] For Rh-catalyzed [3+2] cycloaddition reaction of (non-donor – acceptor) vinylcyclopropanes, see review: L. Jiao, Z.-X. Yu, J. Org. Chem. 2013, 78, 6842 – 6848. [8] a) A. F. G. Goldberg, B. M. Stoltz, Org. Lett. 2011, 13, 4474 – 4476; b) B. M. Trost, P. J. Morris, Angew. Chem. Int. Ed. 2011, 50, 6167 – 6170; Angew. Chem. 2011, 123, 6291 – 6294; c) L.-y. Mei, Y. Wei, Q. Xu, M. Shi, Organometallics 2012, 31, 7591 – 7599; d) B. M. Trost, P. J. Morris, S. J. Sprague, J. Am. Chem. Soc. 2012, 134, 17823 – 17831. [9] a) K. Yamamoto, T. Ishida, J. Tsuji, Chem. Lett. 1987, 16, 1157 – 1158; b) L.-y. Mei, Y. Wei, Q. Xu, M. Shi, Organometallics 2013, 32, 3544 – 3556. [10] N. Ono in The Nitro Group in Organic Synthesis, Wiley, 2002, pp. 231 – 301. For some selected examples: a) N. Takenaka, R. S. Sarangthem, S. K. Seerla, Org. Lett. 2007, 9, 2819 – 2822; b) X.-Y. Guan, Y. Wei, M. Shi, Org. Lett. 2010, 12, 5024 – 5027; c) M. Rueping, A. Kuenkel, R. Frçhlich, Chem. Eur. J. 2010, 16, 4173 – 4176; d) B. M. Trost, D. A. Bringley, P. S. Seng, Org. Lett. 2012, 14, 234 – 237; e) K. Albertshofer, B. Tan, C. F. Barbas, Org. Lett. 2012, 14, 1834 – 1837; f) B.-C. Hong, P.-Y. Chen, P. Kotame, P.-Y. Lu, G.-H. Lee, J.-H. Liao, Chem. Commun. 2012, 48, 7790 – 7792; g) B. M. Trost, D. A. Bringley, B. M. O’Keefe, Org. Lett. 2013, 15, 5630 – 5633. a) G. Feuer in Progress in Medicinal Chemistry, Vol. 10 (Eds.: G. P. Ellis, G. B. West), Elsevier, 1974, pp. 85 – 158; b) K. A. Bello, L. Cheng, J. Griffiths, J. Chem. Soc. Perkin Trans. 2 1987, 815 – 818; c) D. Leblois, S. Piessard, G. Le Baut, P. Kumar, J.-D. Brion, L. Sparfel, R.-Y. Sanchez, M. Juge, J.-Y. Petit, L. Welin, Eur. J. Med. Chem. 1987, 22, 229 – 238; d) M. R. Bryce, S. R. Davies, M. Hasan, G. J. Ashwell, M. Szablewski, M. G. B. Drew, R. Short, M. B. Hursthouse, J. Chem. Soc. Perkin Trans. 2 1989, 1285 – 1292; e) D. B. Hansen, M. M. Joullie, Chem. Soc. Rev. 2005, 34, 408 – 417. a) D. L. Boger, I. C. Jacobson, J. Org. Chem. 1990, 55, 1919 – 1928; b) J. A. Wendt, P. J. Gauvreau, R. D. Bach, J. Am. Chem. Soc. 1994, 116, 9921 – 9926. B. A. Brooks, E. M. Blair, R. Finch, A. F. Lant, Br. J. Clin. Pharmacol. 1980, 10, 249 – 258. a) J.-L. Vasse, R. Stranne, R. Zalubovskis, C. Gayet, C. Moberg, J. Org. Chem. 2003, 68, 3258 – 3270; b) R. Zalubovskis, A. Bouet, E. Fjellander, S. Constant, D. Linder, A. Fischer, J. Lacour, T. Privalov, C. Moberg, J. Am. Chem. Soc. 2008, 130, 1845 – 1855. CCDC-1019422 contains 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.

Received: September 25, 2014 Published online on && &&, 0000

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Communication

COMMUNICATION & Asymmetric Catalysis F. Wei, C.-L. Ren, D. Wang, L. Liu* && – &&

Pd catalysis: An enantioselective [3+2] cycloaddition of vinylcyclopropane derived from 1,3-indanedione with nitroalkenes catalyzed by palladium(0) with

Chem. Eur. J. 2014, 20, 1 – 5

a chiral bis(tert-amine) ligand was developed in high yields with good diastereoselectivities and excellent enantioselectivities (see scheme).

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Highly Enantioselective [3+2] Cycloaddition of Vinylcyclopropane with Nitroalkenes Catalyzed by Palladium(0) with a Chiral Bis(tertamine) Ligand

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Highly enantioselective [3+2] cycloaddition of vinylcyclopropane with nitroalkenes catalyzed by palladium(0) with a chiral bis(tert-amine) ligand.

An enantioselective [3+2] cycloaddition of vinyl cyclopropane derived from 1,3-indanedione with nitroalkenes catalyzed by palladium(0) with a chiral b...
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