Asymmetric Construction of Remote Vicinal Quaternary and Tertiary

Letter Cite This: Org. Lett. XXXX, XXX, XXX−XXX

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Asymmetric Construction of Remote Vicinal Quaternary and Tertiary Stereocenters via Direct Doubly Vinylogous Michael Addition Subhrajit Rout,†,§ Harshit Joshi,†,§ and Vinod K. Singh*,†,‡ †

Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP, India Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462 066, MP, India

‡

S Supporting Information *

ABSTRACT: An asymmetric direct doubly vinylogous Michael addition has been developed for the generation of sterically congested vicinal quaternary and tertiary stereocenters. This doubly vinylogous Michael addition of β,γ-unsaturated butenolides to 3-methyl-4-nitro-5-alkenyl isoxazoles, powered by a bifunctional squaramide, affords a broad range of densely functionalized enantioenriched γ,γ-disubstituted butenolides in high yields with excellent diastereo- and enantioselectivities in most cases. Moreover, the strategy highlights the first application of β,γ-unsaturated butenolides in an asymmetric 1,6-conjugate addition. Scheme 1. Catalytic Asymmetric Addition Reactions of γSubstituted β,γ-Unsaturated Butenolides

T

he asymmetric construction of sterically congested vicinal quaternary and tertiary stereocenters is a difficult task in synthetic chemistry1 and has become a subject of great importance, owing to the ubiquity of such stereochemical arrays in natural products and biologically active molecules.2 On the other hand, remote stereocontrol is a noble strategy to access stereocenters at distant positions from reactive functional groups but represents a formidable challenge in asymmetric synthesis.3 In this respect, asymmetric 1,6conjugate addition reactions4 and vinylogous nucleophilic strategies5 have gained considerable attention from synthetic chemists. The reported methodologies for an asymmetric direct vinylogous nucleophilic 1,6-conjugate addition are limited due to the challenges in activation of both the vinylogous substrates at their remote reactive sites to control the regio-, diastereo-, and enantioselectivities and confined to the synthesis of either singular or contiguous tertiary stereocenters.6 However, asymmetric construction of vicinal quaternary and tertiary stereocenters via a direct doubly vinylogous Michael addition is challenging and yet to be accomplished. A chiral γ,γ-disubstituted butenolide unit, a privileged structural framework, is widespread in natural products and biologically active molecules.7 The synthetic importance of chiral γ,γ-disubstituted butenolides lies in their capability to serve as valuable intermediates for the construction of biologically active natural products.8,9 Toward this end, γsubstituted β,γ-unsaturated butenolides9 have been identified as a privileged substrate since Chen’s group described their reaction with Morita−Baylis−Hillman carbonates in the presence of (DHQD)2PYR as organocatalyst.10 The asymmetric additions of β,γ-unsaturated butenolides to isatins and aldimines were beautifully described by Feng’s11a,b and Trost’s groups (Scheme 1A).11c In addition, β,γ-unsaturated butenolides have been heavily employed in an asymmetric vinylogous © XXXX American Chemical Society

Michael addition of various acyclic12 and cyclic electrophilic partners (Scheme 1A).13 Quite surprisingly, and in spite of their extensive use in asymmetric synthesis, γ-substituted β,γunsaturated butenolides, to the best of our knowledge, have not been applied in an enantioselective 1,6-conjugate addition.14 While working on similar area, we recently reported catalytic asymmetric synthesis of γ,γ-disubstituted butenolides by a 1,4conjugate addition.15 Moreover, we have demonstrated an atom-economic16 asymmetric construction of vicinal tertiary stereocenters via a vinylogous Michael addition reaction.17 Herein, we report the first asymmetric direct doubly vinylogous Michael addition of γ-substituted β,γ-unsaturated butenolides to 3-methyl-4-nitro-5-alkenylisoxazoles catalyzed by a cinchoReceived: February 13, 2018

A

DOI: 10.1021/acs.orglett.8b00493 Org. Lett. XXXX, XXX, XXX−XXX

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Organic Letters

diastereo- and enantioselectivities (12:1 dr, 94% ee, entry 5, Table 1). Further, cinchonidine-derived squaramide 1f furnished the product 4aa in 68% yield and excellent dr (12.2:1) with 94% ee (entry 6). The superiority of squaramide over thio(urea) catalysts was probably, owing to the higher N− H acidity of the squaramide moiety, which resulted strong hydrogen bonds with the nitro group of the substrate 3a.25b Quinine (1g) was also examined and was found to yield a mixture of the diastereomeric products in 82% yield, 1:1.6 dr with low enantioselectivity.26 We next turned our attention to investigating the effect of solvents on the reaction. Most of the solvents offered the product in almost the same level of diastereo- and enantioselectivities (entries 8−11), and acetonitrile afforded the product in 30% yield and 7.2:1 dr with 77% ee (entry 12). Solvent studies revealed that the best results were encountered in the case of THF, both in terms of reaction rate and yield of the product (entry 10). The yield, diastereo- and enantioselectivities of the product 4aa could be increased, when the reaction was conducted at 0 °C (86%, 18:1 dr, 97% ee, entry 13). Further studies on catalyst loading did not bring any improvement on the formation of product 4aa (entries 14 and 15). With the optimized reaction conditions (Table 1, entry 13), the generality of direct doubly vinylogous Michael reactions was investigated. Our initial attempt was devoted to exploring the scope of 3-methyl-4-nitro-5-alkenylisoxazoles with αangelica lactone. The results are shown in Scheme 2. The reaction of α-angelica lactone (2a) with various 3-methyl-4nitro-5-alkenylisoxazoles containing an electron-deficient phenyl group furnished the desired products 4ab−ag in high yields, excellent diastereo- and enantioselectivities (up to 88% yield,

nidine-derived bifunctional squaramide (Scheme 1B). This report, to the best of our knowledge, would be the first example of asymmetric construction of remote vicinal quaternary and tertiary stereocenters via a direct doubly vinylogous Michael addition. Notably, 3-methyl-4-nitro-5-alkenylisoxazole18 was selected as a potential electrophilic partner, considering the presence of an isoxazole motif in several biologically active natural products.19 The importance of isoxazole derivatives is also observed from their broad range of biological profiles.20 Needless to say, these are found to be utilized in the synthesis of complex natural products21 and useful compounds.22 An initial experiment comprising α-angelica lactone (2a) as the vinylogous donor and 3-methyl-4-nitro-5-styrylisoxazole (3a) as the vinylogous acceptor in chloroform at room temperature was conducted using cinchonidine-derived bifunctional thiourea 1a as organocatalyst,23 which we utilized previously in a direct vinylogous Michael addition.17 The product was isolated as a mixture of diastereomers (1:4.3 dr) in 62% yield with low enantioselectivity (Table 1, entry 1). Later, Table 1. Optimization Studiesa

entry 1 2 3 4 5 6 7 8 9 10 11 12 13g 14g,h 15g,i

cat. 1a 1b 1c 1d 1e 1f 1g 1f 1f 1f 1f 1f 1f 1f 1f

solvent CHCl3 CHCl3 CHCl3 CHCl3 CHCl3 CHCl3 CHCl3 CH2Cl2 DCE THF toluene CH3CN THF THF THF

time 96 h 96 h 5 days 5 days 72 h 41 h 5 days 41 h 39 h 26 h 65 h 63 h 38 h 44 h 32 h

yieldb(%) e

62 78e 36e 25e 52 68 82e 54 71 82 43 30 86 77 86

drc

eed (%)

1:4.3 1:3 1:2 1:3.5 12:1 12.2:1 1:1.6 12.3:1 12.8:1 12.5:1 9.4:1 7.2:1 18:1 18:1 17.5:1

41 (22)f 64 (9)f 43 (30)f 45(60)f 94 94 0 (−33)f 93 93 94 94 77 97 96 95

Scheme 2. Evaluation of 3-Methyl-4-nitro-5alkenylisoxazolesa−c

a

Reaction conditions: 2a (0.1 mmol), 3a (0.15 mmol), 1 (0.01 mmol), solvent (0.5 mL). bIsolated yield of 4aa. cDetermined by 1H NMR of the crude reaction mixture. dDetermined by chiral HPLC. eIsolated yield of the mixture of diastereomers. fee of major diastereomer in parentheses. gReaction at 0 °C. h5 mol % catalyst loading. i15 mol % catalyst loading.

several quinine-derived thio(urea) bifunctional organocatalysts were screened.24 Quinine-derived urea catalyst 1b furnished the diastereomeric products (1:3 dr) in 78% yield with 64% ee of the minor diastereomer (Table 1, entry 2). No improvement of diastereo- and enantioselectivities was encountered when the catalysts 1c,d were used (Table 1, entries 3 and 4). Inspired by the promising application of bifunctional squaramides, the reaction was carried out with cinchona-derived squaramides 1e,f.25 We were pleased to find that quinine-derived squaramide 1e afforded the product 4aa in 52% yield with very good

a Reaction conditions: 2a (0.3 mmol), 3a (0.45 mmol), 1f (0.03 mmol), THF (1.5 mL). bIsolated yield. cIn all cases, dr was determined by 1H NMR of crude reaction mixture and ee was determined by chiral HPLC.

B


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Organic Letters 16.3:1 dr and 98% ee). Further, 3-methyl-4-nitro-5-alkenylisoxazoles possessing either a para-methyl or methoxy-substituted aryl group yielded the products 4ah−ai with the high level of diastereo- and enantioselectivities. Substrates bearing either a furyl or 5-iodofuryl group reacted smoothly to deliver 4aj−ak in high yields with excellent stereoselectivities (>20:1 dr, 98% ee for both cases). It is noteworthy that the structural combination of furan and γ-butenolide scaffolds has gained enormous attention, owing to their frequent existence in a variety of natural products.27 The reaction of 2a with a thienyl substituted substrate (3l) offered the product 4al in 88% yield, > 20:1 dr and 98% ee. Notably, alkyl-substituted 3-methyl-4nitro-5-alkenylisoxazole 3m tolerated the protocol to furnish the product 4am in 71% yield with >20:1 dr and 94% enantioselectivity. Next, the scope of various γ-substituted β,γ-unsaturated butenolides for this reaction was evaluated (Scheme 3). In this

Figure 1. X-ray structure of 4ad and proposed stereochemical model.

configuration of other doubly vinylogous Michael products were assigned by analogy. To rationalize the observed stereochemical outcome of the reaction, a transition-state model has been proposed (Figure 1). The proposal involves simultaneous activation of the reaction partners by the bifunctional squaramide catalyst (Figure 1). The quinuclidine moiety deprotonates β,γ-unsaturated butenolide 2a to form the anionic nucleophile, while 3-methyl-4-nitro-5-alkenylisoxazole 3d is activated through double H-bonding of the squaramide moiety of the catalyst 1f. Subsequently, attack of the Re face of the H-bonded anionic nucleophile to the Si face of the substrate 3d results in the formation of the major stereoisomer. We then set out to explore the synthetic utility of the resulting enantioenriched γ,γ-disubstituted butenolides. For instance, product 4aa was transformed into 5 by reducing the nitro group selectively with tin chloride in THF/HCl at room temperature (Scheme 4).18b Further, treatment of 4aa with tin chloride in THF/HCl/H2O at reflux temperature furnished compound 6,18b which was then esterified to form 7 in synthetically viable yield without erosion of enantioselectivity (Scheme 4).29 In conclusion, we have developed the first asymmetric direct doubly vinylogous Michael addition of β,γ-unsaturated butenolides to 3-methyl-4-nitro-5-alkenylisoxazoles catalyzed by a cinchonidine-derived bifunctional squaramide. In most cases, the products were afforded in high yields, with excellent diastereo- and enantioselectivities. Moreover, the methodology, to the best of our knowledge, is the first example of asymmetric remote construction of vicinal quaternary and tertiary stereocenters via a direct doubly vinylogous Michael addition. Considering the impressive range of biological properties and synthetic usefulness of both butenolide and isoxazole derivatives, we believe that the obtained products will find application in different disciplines. Further, studies on cleavage of the N−O bond of an isoxazole motif and the functionalization of a γ,γ-disubstituted butenolide framework of the obtained products are underway in our laboratory.

Scheme 3. Evaluation of β,γ-Unsaturated Butenolidesa−c

a

Reaction conditions: 2 (0.30 mmol), 3 (0.45 mmol), 1f (0.03 mmol), THF (1.5 mL). bIsolated yield. cIn all cases, dr was determined by 1H NMR of the crude reaction mixture and ee was determined by chiral HPLC.

respect, alkyl-substituted butenolide 2b reacted with electrophilic partners 3a and 3m to afford the products (4ba, 4bm, respectively) in good yields with excellent stereoselectivities. The γ-substituted butenolide bearing a benzyl group (2c) could be successfully employed in this methodology. Further, a variety of butenolides containing either a phenyl or substituted phenyl group were treated with 3a to access the products 4da− ha in good to high yields and diastereoselectivities, and excellent enantioselectivities in most cases. Later, the practicality of this strategy was probed by carrying out the reaction on a 4 mmol scale of 2a. Product 4aa was produced in similar yield with the same enantio- and diastereoselectivity (84% yield, 18:1 dr, 97% ee, Scheme 4). The absolute stereochemistry of 4ad was determined by Xray crystallographic studies (Figure 1).28 The absolute

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.orglett.8b00493. Experimental procedures and analytical data (PDF)

Scheme 4. Gram-Scale Reaction and Synthetic Transformations

Accession Codes

CCDC 1590023 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_ [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033. C


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Organic Letters

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Chatterjee, I.; Tannert, R.; Melchiorre, P. Chem. Commun. 2013, 49, 4869. (e) Schneider, C.; Abels, F. Org. Biomol. Chem. 2014, 12, 3531. (f) Marcos, V.; Alemán, J. Chem. Soc. Rev. 2016, 45, 6812. (6) (a) Dell’Amico, L.; Albrecht, L.; Naicker, T.; Poulsen, P. H.; Jørgensen, K. A. J. Am. Chem. Soc. 2013, 135, 8063. (b) Gu, X.; Guo, T.; Dai, Y.; Franchino, A.; Fei, J.; Zou, C.; Dixon, D. J.; Ye, J. Angew. Chem., Int. Ed. 2015, 54, 10249. (c) Li, X.; Xu, X.; Wei, W.; Lin, A.; Yao, H. Org. Lett. 2016, 18, 428. (d) Chen, X.-Y.; Liu, Q.; Chauhan, P.; Li, S.; Peuronen, A.; Rissanen, K.; Jafari, E.; Enders, D. Angew. Chem., Int. Ed. 2017, 56, 6241. (7) (a) Bister, B.; Bischoff, D.; Ströbele, M.; Riedlinger, J.; Reicke, A.; Wolter, F.; Bull, A. T.; Zähner, H.; Fiedler, H.-P.; Süssmuth, R. D. Angew. Chem., Int. Ed. 2004, 43, 2574. (b) Keller, S.; Schadt, H. S.; Ortel, I.; Süssmuth, R. D. Angew. Chem., Int. Ed. 2007, 46, 8284. (c) Zhang, F.; Wang, J.-S.; Gu, Y.-C.; Kong, L.-Y. J. Nat. Prod. 2010, 73, 2042. (d) Zhao, B.-X.; Wang, Y.; Zhang, D.-M.; Jiang, R.-W.; Wang, G.-C.; Shi, J.- M.; Huang, X.-J.; Chen, W.-M.; Che, C.-T.; Ye, W.-C. Org. Lett. 2011, 13, 3888. (8) Nicolaou, K. C.; Harrison, S. T. J. Am. Chem. Soc. 2007, 129, 429. (9) Mao, B.; Fañanás-Mastral, M.; Feringa, B. L. Chem. Rev. 2017, 117, 10502. (10) Cui, H.-L.; Huang, J.-R.; Lei, J.; Wang, Z.-F.; Chen, S.; Wu, L.; Chen, Y.-C. Org. Lett. 2010, 12, 720. (11) (a) Tang, Q.; Lin, L.; Ji, J.; Hu, H.; Liu, X.; Feng, X. Chem. - Eur. J. 2017, 23, 16447. (b) Zhou, L.; Lin, L.; Ji, J.; Xie, M.; Liu, X.; Feng, X. Org. Lett. 2011, 13, 3056. (c) Trost, B. M.; Gnanamani, E.; Tracy, J. S.; Kalnmals, C. A. J. Am. Chem. Soc. 2017, 139, 18198. (12) (a) Quintard, A.; Lefranc, A.; Alexakis, A. Org. Lett. 2011, 13, 1540. (b) Manna, M. S.; Kumar, V.; Mukherjee, S. Chem. Commun. 2012, 48, 5193. (c) Zhang, W.; Tan, D.; Lee, R.; Tong, G.; Chen, W.; Qi, B.; Huang, K.-W.; Tan, C.-H.; Jiang, Z. Angew. Chem., Int. Ed. 2012, 51, 10069. (d) Kumar, V.; Ray, B.; Rathi, P.; Mukherjee, S. Synthesis 2013, 45, 1641. (e) Yang, D.; Wang, L.; Zhao, D.; Han, F.; Zhang, B.; Wang, R. Chem. - Eur. J. 2013, 19, 4691. (f) Das, U.; Chen, Y.-R.; Tsai, Y.-L.; Lin, W. Chem. - Eur. J. 2013, 19, 7713. (g) Ji, J.; Lin, L.; Zhou, L.; Zhang, Y.; Liu, Y.; Liu, X.; Feng, X. Adv. Synth. Catal. 2013, 355, 2764. (h) Li, X.; Lu, M.; Dong, Y.; Wu, W.; Qian, Q.; Ye, J.; Dixon, D. J. Nat. Commun. 2014, 5, 4479. (i) Yin, L.; Takada, H.; Lin, S.; Kumagai, N.; Shibasaki, M. Angew. Chem., Int. Ed. 2014, 53, 5327. (j) Sekikawa, T.; Kitaguchi, T.; Kitaura, H.; Minami, T.; Hatanaka, Y. Org. Lett. 2015, 17, 3026. (k) Wang, Z.-H.; Wu, Z.-J.; Huang, X.-Q.; Yue, D.-F.; You, Y.; Xu, X.-Y.; Zhang, X.-M.; Yuan, W.-C. Chem. Commun. 2015, 51, 15835. (l) Simlandy, A. K.; Mukherjee, S. Org. Biomol. Chem. 2016, 14, 5659. (m) Lagoutte, R.; Besnard, C.; Alexakis, A. Eur. J. Org. Chem. 2016, 2016, 4372. (n) Zhang, M.; Kumagai, N.; Shibasaki, M. Chem. - Eur. J. 2016, 22, 5525. (o) Ji, J.; Lin, L.; Tang, Q.; Kang, T.; Liu, X.; Feng, X. ACS Catal. 2017, 7, 3763. (13) (a) Manna, M. S.; Mukherjee, S. Chem. - Eur. J. 2012, 18, 15277. (b) Guo, Y.-L.; Jia, L.-N.; Peng, L.; Qi, L.-W.; Zhou, J.; Tian, F.; Xu, X.-Y.; Wang, L.-X. RSC Adv. 2013, 3, 16973. (c) Manna, M. S.; Mukherjee, S. Chem. Sci. 2014, 5, 1627. (14) (a) Wu, Y.; Singh, R. P.; Deng, L. J. Am. Chem. Soc. 2011, 133, 12458. (b) Quintard, A.; Alexakis, A. Chem. Commun. 2011, 47, 7212. (c) Kumar, V.; Mukherjee, S. Chem. Commun. 2013, 49, 11203. (d) Li, C.; Jiang, K.; Chen, Y.-C. Molecules 2015, 20, 13642. (e) Wu, B.; Yu, Z.; Gao, X.; Lan, Y.; Zhou, Y.-G. Angew. Chem., Int. Ed. 2017, 56, 4006. (15) Rout, S.; Das, A.; Singh, V. K. Chem. Commun. 2017, 53, 5143. (16) Trost, B. M. Science 1991, 254, 1471. (17) Rout, S.; Ray, S. K.; Unhale, R. A.; Singh, V. K. Org. Lett. 2014, 16, 5568. (18) (a) Baschieri, A.; Bernardi, L.; Ricci, A.; Suresh, S.; Adamo, M. F. A. Angew. Chem., Int. Ed. 2009, 48, 9342. (b) Pei, Q.-L.; Sun, H.-W.; Wu, Z.-J.; Du, X.-L.; Zhang, X.-M.; Yuan, W.-C. J. Org. Chem. 2011, 76, 7849. (c) Fiandra, C. D.; Piras, L.; Fini, F.; Disetti, P.; Moccia, M.; Adamo, M. F. A. Chem. Commun. 2012, 48, 3863. (d) Zhang, J.; Liu, X.; Ma, X.; Wang, R. Chem. Commun. 2013, 49, 9329. (e) Liu, X.-L.; Han, W.-Y.; Zhang, X.-M.; Yuan, W.-C. Org. Lett. 2013, 15, 1246. (f) Chauhan, P.; Mahajan, S.; Raabe, G.; Enders, D. Chem. Commun. 2015, 51, 2270.

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Vinod K. Singh: 0000-0003-0928-5543 Author Contributions §

S.R. and H.J. contributed equally.

Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS V.K.S. thanks the Department of Science and Technology, India, for a J. C. Bose fellowship and SERB, DST (EMR/2014/ 001165), for a research grant. H.J. is grateful to the University Grants Commission (UGC), New Delhi, India, for a doctoral fellowship. We are thankful to Vierandra Kumar, IIT Kanpur, for assistance with X-ray crystallography.

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DEDICATION This work is dedicated to Professor Elias J. Corey on the occasion of his 90th birthday. REFERENCES

(1) Selected reviews: (a) Corey, E. J.; Guzman-Perez, A. Angew. Chem., Int. Ed. 1998, 37, 388. (b) Christoffers, J.; Mann, A. Angew. Chem., Int. Ed. 2001, 40, 4591. (c) Douglas, C. J.; Overman, L. E. Proc. Natl. Acad. Sci. U. S. A. 2004, 101, 5363. (d) Ito, H.; Taguchi, T. Chem. Soc. Rev. 1999, 28, 43. (e) Martín Castro, A. Chem. Rev. 2004, 104, 2939. Selected examples: (f) Taylor, M. S.; Jacobsen, E. N. J. Am. Chem. Soc. 2003, 125, 11204. (g) Li, H.; Wang, Y.; Tang, L.; Wu, F.; Liu, X.; Guo, C.; Foxman, B. M.; Deng, L. Angew. Chem., Int. Ed. 2005, 44, 105. (h) Mase, N.; Thayumanavan, R.; Tanaka, F.; Barbas, C. F., III Org. Lett. 2004, 6, 2527. (i) Chauhan, P.; Chimni, S. S. Adv. Synth. Catal. 2011, 353, 3203. (j) Chen, W.; Hartwig, J. F. J. Am. Chem. Soc. 2013, 135, 2068. (k) Liu, W.-B.; Reeves, C. M.; Virgil, S. C.; Stoltz, B. M. J. Am. Chem. Soc. 2013, 135, 10626. (l) Liu, W.-B.; Reeves, C.-M.; Stoltz, B. M. J. Am. Chem. Soc. 2013, 135, 17298. (m) Chen, W.; Hartwig, J. F. J. Am. Chem. Soc. 2014, 136, 377. (2) Corey, E. J.; Cheng, X.-M. The Logic of Chemical Synthesis; John Wiley & Sons: New York, 1995. (3) Recent reports: (a) Werner, E. W.; Mei, T.-S.; Burckle, A. J.; Sigman, M. S. Science 2012, 338, 1455. (b) Jiang, H.; Albrecht, Ł.; Jørgensen, K. A. Chem. Sci. 2013, 4, 2287. (c) Mei, T.-S.; Patel, H. H.; Sigman, M. S. Nature 2014, 508, 340. (d) Byrne, L.; Solà, J.; Boddaert, T.; Marcelli, T.; Adams, R. W.; Morris, G. A.; Clayden, J. Angew. Chem., Int. Ed. 2014, 53, 151. (e) Patel, H. H.; Sigman, M. S. J. Am. Chem. Soc. 2015, 137, 3462. (f) Naganawa, Y.; Kawagishi, M.; Ito, J.-I.; Nishiyama, H. Angew. Chem., Int. Ed. 2016, 55, 6873. (g) Zhu, S.; Niljianskul, N.; Buchwald, S. L. Nat. Chem. 2016, 8, 144. (4) For reviews, see: (a) Csákÿ, A. G.; de la Herrán, G.; Murcia, M. C. Chem. Soc. Rev. 2010, 39, 4080. (b) Biju, A. T. ChemCatChem 2011, 3, 1847. (c) Chauhan, P.; Kaya, U.; Enders, D. Adv. Synth. Catal. 2017, 359, 888. Selected examples: (d) Bernardi, L.; López-Cantarero, J.; Niess, B.; Jørgensen, K. A. J. Am. Chem. Soc. 2007, 129, 5772. (e) Uraguchi, D.; Yoshioka, K.; Ueki, Y.; Ooi, T. J. Am. Chem. Soc. 2012, 134, 19370. (f) Hénon, H.; Mauduit, M.; Alexakis, A. Angew. Chem., Int. Ed. 2008, 47, 9122. (g) Sawano, T.; Ashouri, A.; Nishimura, T.; Hayashi, T. J. Am. Chem. Soc. 2012, 134, 18936. (h) Meng, F.; Li, X.; Torker, S.; Shi, Y.; Shen, X.; Hoveyda, A. H. Nature 2016, 537, 387. (5) Selected reviews: (a) Denmark, S. E.; Heemstra, J. R.; Beutner, G. L. Angew. Chem., Int. Ed. 2005, 44, 4682. (b) Cui, H.-L.; Chen, Y.-C. Chem. Commun. 2009, 4479. (c) Casiraghi, G.; Battistini, L.; Curti, C.; Rassu, G.; Zanardi, F. Chem. Rev. 2011, 111, 3076. (d) Jurberg, I. D.; D


Letter

Organic Letters (19) Johnston, G. A. R. Neurochem. Res. 2014, 39, 1942. (20) (a) Daidone, G.; Raffa, D.; Maggio, B.; Plescia, F.; Cutuli, V. M. C.; Mangano, N. G.; Caruso, A. Arch. Pharm. Pharm. Med. Chem. 1999, 332, 50. (b) Talley, J. J.; Brown, D. L.; Carter, J. S.; Graneto, M. J.; Koboldt, C. M.; Masferrer, J. L.; Perkins, W. E.; Rogers, R. S.; Shaffer, A. F.; Zhang, Y. Y.; Zweifel, B. S.; Seibert, K. J. Med. Chem. 2000, 43, 775. (c) Li, W.-T.; Hwang, D.-R.; Chen, C.-P.; Shen, C.-W.; Huang, C.-L.; Chen, T.-W.; Lin, C.-H.; Chang, Y.-L.; Chang, Y.-Y.; Lo, Y.-K.; Tseng, H.-Y.; Lin, C.-C.; Song, J.-S.; Chen, H.-C.; Chen, S.-J.; Wu, S.H.; Chen, C.-T. J. Med. Chem. 2003, 46, 1706. (d) Carr, J. B.; Durham, H. G.; Hass, D. K. J. Med. Chem. 1977, 20, 934. (e) Jacobsen, N.; Pedersen, L.-E. K.; Wengel, A. Pestic. Sci. 1990, 29, 95. (21) (a) Stork, G.; McMurry, J. E. J. Am. Chem. Soc. 1967, 89, 5464. (b) Stevens, R. V.; Christensen, C. G.; Cory, R. M.; Thorsett, E. J. Am. Chem. Soc. 1975, 97, 5940. (c) Smith, A. L.; Hwang, C.-K.; Pitsinos, E.; Scarlato, G. R.; Nicolaou, K. C. J. Am. Chem. Soc. 1992, 114, 3134. (d) Charest, M. G.; Lerner, C. D.; Brubaker, J. D.; Siegel, D. R.; Myers, A. G. Science 2005, 308, 395. (22) Adamo, M. F. A.; Nagabelli, M. Org. Lett. 2008, 10, 1807. (23) Li, B.- J.; Jiang, L.; Liu, M.; Chen, Y.-C.; Ding, L.-S.; Wu, Y. Synlett 2005, 603. (24) (a) Vakulya, B.; Varga, S.; Csámpai, A.; Soós, T. Org. Lett. 2005, 7, 1967. (b) Ye, J.; Dixon, D. J.; Hynes, P. S. Chem. Commun. 2005, 4481. (c) Connon, S. J. Chem. - Eur. J. 2006, 12, 5418. (d) Connon, S. J. Chem. Commun. 2008, 2499. (e) Doyle, A. G.; Jacobsen, E. N. Chem. Rev. 2007, 107, 5713. (25) (a) Malerich, J. P.; Hagihara, K.; Rawal, V. H. J. Am. Chem. Soc. 2008, 130, 14416. (b) Chauhan, P.; Mahajan, S.; Kaya, U.; Hack, D.; Enders, D. Adv. Synth. Catal. 2015, 357, 253. (26) Song, C. E., Ed. Cinchona Alkaloids in Synthesis and Catalysis; Wiley-VCH Verlag: Weinheim, 2009. (27) Roethle, P. A.; Trauner, D. Nat. Prod. Rep. 2008, 25, 298. (28) For details, see the Supporting Information. (29) Rao, C. G. Org. Prep. Proced. Int. 1980, 12, 225.

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Asymmetric Construction of Remote Vicinal Quaternary and Tertiary

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