Catalytic enantioselective construction of all-carbon quaternary stereocenters: Synthetic and mechanistic studies of the C-acylation of silyl ketene acetals

Journal of the American Chemical Society

Volumn 127, Issue 15, 2005, Pages 5604-5607

  Mermerian, Ara H ^a   Fu, Gregory C ^a  

^a MASSACHUSETTS INSTITUTE OF TECHNOLOGY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CARBON; CATALYSTS; KETONES;

ACYCLIC SILYL KETENE; ANHYDRIDES; CATALYTIC ENANTIOSELECTIVE CONSTRUCTION; ELECTROPHILES;

STEREOCHEMISTRY;

ACETAL DERIVATIVE; CARBON; CARBONYL DERIVATIVE; KETENE DERIVATIVE; PYRIDINIUM DERIVATIVE;

ACYLATION; ARTICLE; CATALYSIS; CHIRALITY; ENANTIOSELECTIVITY; SYNTHESIS;

ACETALS; ACYLATION; ANHYDRIDES; CATALYSIS; ETHYLENES; KETONES; PYRIDINIUM COMPOUNDS; SILANES; STEREOISOMERISM;

EID: 17644423068     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja043832w     Document Type: Article

References (36)

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2. For very recent reviews with leading references, see: (a) Denissova, I.; Barriault, L. Tetrahedron 2003, 59, 10105-10146. (b) Douglas, C. J.; Overman, L. E. Proc. Natl. Acad. Sci. U.S.A. 2004, 101, 5363-5367.
3. Clearly, not all processes fall within this analysis (e.g., asymmetric cyclopropanations of olefins).
4. (a) For a preliminary communication, see: Mermerian, A. H.; Fu, G. C. J. Am. Chem. Soc. 2003, 125, 4050-4051.
5. (b) For a study of the catalytic asymmetric acylation of silyl ketene imines, see: Mermerian, A. H.; Fu, G. C. Angew. Chem., Int. Ed. 2005, 44, 949-952.
6. For reviews of catalytic asymmetric aldol reactions, see: (a) Carreira, E. M. In Comprehensive Asymmetric Catalysis; Jacobsen, E. N., Pfaltz, A., Yamamoto, H., Eds.; Springer: New York, 1999; Chapter 29.1. (b) Machajewski, T. D.; Wong, C.-H. Angew. Chem., Int. Ed. 2000, 39, 1352-1374.
7. For reviews of catalytic asymmetric aldol reactions, see: (a) Carreira, E. M. In Comprehensive Asymmetric Catalysis; Jacobsen, E. N., Pfaltz, A., Yamamoto, H., Eds.; Springer: New York, 1999; Chapter 29.1. (b) Machajewski, T. D.; Wong, C.-H. Angew. Chem., Int. Ed. 2000, 39, 1352-1374.
8. The effective use of covalently bound chiral auxiliaries to achieve the asymmetric acylation of enolates has been described. For pioneering studies, see: (a) Evans, D. A.; Ennis, M. D.; Le, T., Mandel, N.; Mandel, G. J. Am. Chem. Soc. 1984, 106, 1154-1156. (b) Ito, Y.; Katsuki, T.; Yamaguchi, M. Tetrahedron Lett. 1984, 25, 6015-6016.
9. The effective use of covalently bound chiral auxiliaries to achieve the asymmetric acylation of enolates has been described. For pioneering studies, see: (a) Evans, D. A.; Ennis, M. D.; Le, T., Mandel, N.; Mandel, G. J. Am. Chem. Soc. 1984, 106, 1154-1156. (b) Ito, Y.; Katsuki, T.; Yamaguchi, M. Tetrahedron Lett. 1984, 25, 6015-6016.
10. At the outset of our investigation, we were aware of only one example of a nucleophile-catalyzed C-acylation: the TBAF-catalyzed C-acylation of silyl enol ethers with acyl cyanides. See: Wiles, C.; Watts, P.; Haswell, S. J.; Pombo-Villar, E. Tetrahedron Lett. 2002, 43, 2945-2948.
11. For an overview and leading references, see: Fu, G. C. Acc. Chem. Res. 2004, 37, 542-547.
12. For examples of O-to-C rearrangements catalyzed by such complexes, see: (a) Hills, I. D.; Fu, G. C. Angew. Chem., Int. Ed. 2003, 42, 3921-3924. (b) Ruble, J. C.; Fu, G. C. J. Am. Chem. Soc. 1998, 120, 11532-11533.
13. For examples of O-to-C rearrangements catalyzed by such complexes, see: (a) Hills, I. D.; Fu, G. C. Angew. Chem., Int. Ed. 2003, 42, 3921-3924. (b) Ruble, J. C.; Fu, G. C. J. Am. Chem. Soc. 1998, 120, 11532-11533.
14. For examples of other methods for the catalytic asymmetric synthesis of β-ketoesters that contain an all-carbon quaternary stereocenter in the α position, see: (a) Nemoto, T.; Matsumoto, T.; Masuda, T.; Hitomi, T.; Hatano, K.; Hamada, Y. J. Am. Chem. Soc. 2004, 126, 3690-3691. (b) Ooi, T.; Miki, T.; Taniguchi, M.; Shiraishi, M.; Takeuchi, M.; Maruoka, K. Angew. Chem., Int. Ed. 2003, 42, 3796-3798. (c) Hamashima, Y.; Hotta, D.; Sodeoka, M. J. Am. Chem. Soc. 2002, 124, 11240-11241. (d) Yang, D.; Gu, S.; Yan, Y.-L.; Zhu, N.-Y.; Cheung, K.-K. J. Am. Chem. Soc. 2001, 123, 8612-8613. (e) Trost, B. M.; Radinov, R.; Grenzer, E. M. J. Am. Chem. Soc. 1997, 119, 7879-7880.
15. For examples of other methods for the catalytic asymmetric synthesis of β-ketoesters that contain an all-carbon quaternary stereocenter in the α position, see: (a) Nemoto, T.; Matsumoto, T.; Masuda, T.; Hitomi, T.; Hatano, K.; Hamada, Y. J. Am. Chem. Soc. 2004, 126, 3690-3691. (b) Ooi, T.; Miki, T.; Taniguchi, M.; Shiraishi, M.; Takeuchi, M.; Maruoka, K. Angew. Chem., Int. Ed. 2003, 42, 3796-3798. (c) Hamashima, Y.; Hotta, D.; Sodeoka, M. J. Am. Chem. Soc. 2002, 124, 11240-11241. (d) Yang, D.; Gu, S.; Yan, Y.-L.; Zhu, N.-Y.; Cheung, K.-K. J. Am. Chem. Soc. 2001, 123, 8612-8613. (e) Trost, B. M.; Radinov, R.; Grenzer, E. M. J. Am. Chem. Soc. 1997, 119, 7879-7880.
16. For examples of other methods for the catalytic asymmetric synthesis of β-ketoesters that contain an all-carbon quaternary stereocenter in the α position, see: (a) Nemoto, T.; Matsumoto, T.; Masuda, T.; Hitomi, T.; Hatano, K.; Hamada, Y. J. Am. Chem. Soc. 2004, 126, 3690-3691. (b) Ooi, T.; Miki, T.; Taniguchi, M.; Shiraishi, M.; Takeuchi, M.; Maruoka, K. Angew. Chem., Int. Ed. 2003, 42, 3796-3798. (c) Hamashima, Y.; Hotta, D.; Sodeoka, M. J. Am. Chem. Soc. 2002, 124, 11240-11241. (d) Yang, D.; Gu, S.; Yan, Y.-L.; Zhu, N.-Y.; Cheung, K.-K. J. Am. Chem. Soc. 2001, 123, 8612-8613. (e) Trost, B. M.; Radinov, R.; Grenzer, E. M. J. Am. Chem. Soc. 1997, 119, 7879-7880.
17. For examples of other methods for the catalytic asymmetric synthesis of β-ketoesters that contain an all-carbon quaternary stereocenter in the α position, see: (a) Nemoto, T.; Matsumoto, T.; Masuda, T.; Hitomi, T.; Hatano, K.; Hamada, Y. J. Am. Chem. Soc. 2004, 126, 3690-3691. (b) Ooi, T.; Miki, T.; Taniguchi, M.; Shiraishi, M.; Takeuchi, M.; Maruoka, K. Angew. Chem., Int. Ed. 2003, 42, 3796-3798. (c) Hamashima, Y.; Hotta, D.; Sodeoka, M. J. Am. Chem. Soc. 2002, 124, 11240-11241. (d) Yang, D.; Gu, S.; Yan, Y.-L.; Zhu, N.-Y.; Cheung, K.-K. J. Am. Chem. Soc. 2001, 123, 8612-8613. (e) Trost, B. M.; Radinov, R.; Grenzer, E. M. J. Am. Chem. Soc. 1997, 119, 7879-7880.
18. For examples of other methods for the catalytic asymmetric synthesis of β-ketoesters that contain an all-carbon quaternary stereocenter in the α position, see: (a) Nemoto, T.; Matsumoto, T.; Masuda, T.; Hitomi, T.; Hatano, K.; Hamada, Y. J. Am. Chem. Soc. 2004, 126, 3690-3691. (b) Ooi, T.; Miki, T.; Taniguchi, M.; Shiraishi, M.; Takeuchi, M.; Maruoka, K. Angew. Chem., Int. Ed. 2003, 42, 3796-3798. (c) Hamashima, Y.; Hotta, D.; Sodeoka, M. J. Am. Chem. Soc. 2002, 124, 11240-11241. (d) Yang, D.; Gu, S.; Yan, Y.-L.; Zhu, N.-Y.; Cheung, K.-K. J. Am. Chem. Soc. 2001, 123, 8612-8613. (e) Trost, B. M.; Radinov, R.; Grenzer, E. M. J. Am. Chem. Soc. 1997, 119, 7879-7880.
19. For a recent review of catalytic asymmetric processes that exploit dual activation of the electrophile and the nucleophile, see: Ma, J.-A.; Canard, D. Angew. Chem., Int. Ed. 2004, 43, 4566-4583.
20. (a) One preliminary example of an asymmetric C-acylation of an acyclic ketene acetal was described in our initial report (20% catalyst loading; ref 3a).
21. (b) The ee of the product does not erode upon exposure to the catalyst for an extended period of time, which establishes that C-acylation is irreversible.
22. (c) Silyl ketene acetals in which the aryl group is replaced with an alkyl substituent are not suitable substrates, presumably due to a reluctance to participate in acetate-induced desilylation to form an ester enolate (vide infra).
23. The presence of a bulky aryl group (e.g., 1-naphthyl) leads to significant (sometimes exclusive) O-acylation, presumably due to steric hindrance to acylation at carbon.
24. We have not pursued a separate optimization of the ee for this family of substrates.
25. For leading references to the chemistry of DMAP, see: Spivey, A. C.; Arseniyadis, S. Angew. Chem., Int. Ed. 2004, 43, 5436-5441.
26. The presence of an α-aryl substituent facilitates this process, since the aryl group allows delocalization of the enolate anion.
27. For a closely related process, see: Pfaltz, A.; Lautens, M. In Comprehensive Asymmetric Catalysis; Jacobsen, E. N., Pfaltz, A., Yamamoto, H., Eds.; Springer: New York, 1999; pp 858-859.
28. For early studies of fluoride-catalyzed aldol reactions of silyl enol ethers, see: (a) Noyori, R.; Yokoyama, K.; Sakata, J.; Kuwajima, I.; Nakamura, E.; Shimizu, M. J. Am. Chem. Soc. 1977, 99, 1265-1267. (b) Nakamura, E.; Shimizu, M.; Kuwajima, I.; Sakata, J.; Yokoyama, K.; Noyori, R. J. Org. Chem. 1983, 48, 932-945. (c) Nakamura, E.; Yamago, S.; Machii, D.; Kuwajima, I. Tetrahedron Lett. 1988, 29, 2207-2210. (d) Yamago, S.; Machii, D.; Nakamura, E. J. Org. Chem. 1991, 56, 2098-2106. (e) Denmark, S. E.; Lee, W. J. Org. Chem. 1994, 59, 707-709.
29. For early studies of fluoride-catalyzed aldol reactions of silyl enol ethers, see: (a) Noyori, R.; Yokoyama, K.; Sakata, J.; Kuwajima, I.; Nakamura, E.; Shimizu, M. J. Am. Chem. Soc. 1977, 99, 1265-1267. (b) Nakamura, E.; Shimizu, M.; Kuwajima, I.; Sakata, J.; Yokoyama, K.; Noyori, R. J. Org. Chem. 1983, 48, 932-945. (c) Nakamura, E.; Yamago, S.; Machii, D.; Kuwajima, I. Tetrahedron Lett. 1988, 29, 2207-2210. (d) Yamago, S.; Machii, D.; Nakamura, E. J. Org. Chem. 1991, 56, 2098-2106. (e) Denmark, S. E.; Lee, W. J. Org. Chem. 1994, 59, 707-709.
30. For early studies of fluoride-catalyzed aldol reactions of silyl enol ethers, see: (a) Noyori, R.; Yokoyama, K.; Sakata, J.; Kuwajima, I.; Nakamura, E.; Shimizu, M. J. Am. Chem. Soc. 1977, 99, 1265-1267. (b) Nakamura, E.; Shimizu, M.; Kuwajima, I.; Sakata, J.; Yokoyama, K.; Noyori, R. J. Org. Chem. 1983, 48, 932-945. (c) Nakamura, E.; Yamago, S.; Machii, D.; Kuwajima, I. Tetrahedron Lett. 1988, 29, 2207-2210. (d) Yamago, S.; Machii, D.; Nakamura, E. J. Org. Chem. 1991, 56, 2098-2106. (e) Denmark, S. E.; Lee, W. J. Org. Chem. 1994, 59, 707-709.
31. For early studies of fluoride-catalyzed aldol reactions of silyl enol ethers, see: (a) Noyori, R.; Yokoyama, K.; Sakata, J.; Kuwajima, I.; Nakamura, E.; Shimizu, M. J. Am. Chem. Soc. 1977, 99, 1265-1267. (b) Nakamura, E.; Shimizu, M.; Kuwajima, I.; Sakata, J.; Yokoyama, K.; Noyori, R. J. Org. Chem. 1983, 48, 932-945. (c) Nakamura, E.; Yamago, S.; Machii, D.; Kuwajima, I. Tetrahedron Lett. 1988, 29, 2207-2210. (d) Yamago, S.; Machii, D.; Nakamura, E. J. Org. Chem. 1991, 56, 2098-2106. (e) Denmark, S. E.; Lee, W. J. Org. Chem. 1994, 59, 707-709.
32. For early studies of fluoride-catalyzed aldol reactions of silyl enol ethers, see: (a) Noyori, R.; Yokoyama, K.; Sakata, J.; Kuwajima, I.; Nakamura, E.; Shimizu, M. J. Am. Chem. Soc. 1977, 99, 1265-1267. (b) Nakamura, E.; Shimizu, M.; Kuwajima, I.; Sakata, J.; Yokoyama, K.; Noyori, R. J. Org. Chem. 1983, 48, 932-945. (c) Nakamura, E.; Yamago, S.; Machii, D.; Kuwajima, I. Tetrahedron Lett. 1988, 29, 2207-2210. (d) Yamago, S.; Machii, D.; Nakamura, E. J. Org. Chem. 1991, 56, 2098-2106. (e) Denmark, S. E.; Lee, W. J. Org. Chem. 1994, 59, 707-709.
33. 6 does not affect the enantioselectivity of C-acylations of silyl ketene acetals catalyzed by 1.
34. 1H NMR study has shown that the resting state of the catalyst during the catalytic cycle is the unacylated species (i.e., structure 1).
35. The aromatic substituent is expected to lower the barrier to interconversion, relative to an enolate that bears only alkyl groups.
36. For a discussion of open transition states in the context of Mukaiyama aldol reactions, see ref 4a.