Diastereoselective addition of prochiral metallo enolates to chiral 1- acylpyridinium salts [28]

Journal of the American Chemical Society

Volumn 121, Issue 11, 1999, Pages 2651-2652

  Comins, Daniel L ^a   Kuethe, Jeffrey T ^a   Hong, Hao ^a   Lakner, Frederick J ^a   Concolino, Thomas E ^b   Rheingold, Arnold L ^b  

^a NORTH CAROLINA STATE UNIVERSITY   (United States)

^b UNIVERSITY OF DELAWARE   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

DIHYDROPYRIDONE; KETONE; LACTONE; NATURAL PRODUCT; PYRIDINIUM DERIVATIVE; UNCLASSIFIED DRUG;

CHEMICAL STRUCTURE; CHIRALITY; CRYSTAL STRUCTURE; DIASTEREOISOMER; LETTER; PROTON NUCLEAR MAGNETIC RESONANCE; STEREOCHEMISTRY; SYNTHESIS;

EID: 0033599533     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja990024+     Document Type: Letter

References (22)

1. (a) Comins, D. L.; Joseph, S. P.; Goehring, R. R. J. Am. Chem. Soc. 1994, 116, 4719.
2. (b) Comins, D. L.; Guerra-Weltzien, L. Tetrahedron Lett. 1996, 37, 3807 and references cited therein.
3. (a) Comins, D. L.; Foti, C. J.; Libby, A. H. Heterocycles 1998, 48, 1313.
4. (b) Comins, D. L.; Stolze, D. A.; Thakker, P.; McArdle, C. L. Tetrahedron Lett. 1998, 39, 5693.
5. (a) Comins, D. L.; Hong, H. J. Org. Chem. 1993, 58, 5035.
6. (b) Comins, D. L.; Hong, H. J. Am. Chem. Soc. 1993, 115, 8851.
7. We assume that the E/Z ratio of the zinc enolate is similar to that reported for the lithium enolate (E/Z = 70/30) prepared using LDA, see: Heathcock, C. H.; Buse, C. T.; Kleschick, W. A.; Pirrung, M. C.; Sohn, J. E.; Lampe, J. J. Org. Chem. 1980, 45, 1066.
8. (a) Comins, D. L.; Salvador, J. M. J. Org. Chem. 1993, 58, 4656.
9. (b) (+)- and (-)-TCC alcohols are available from Aldrich Chemical Co.
10. Details can be found in the Supporting Information.
11. Available from Aldrich Chemical Co.
12. Araki, Y.; Nagasawa, J.; Yoshiharu, I. J. Chem. Soc., Perkin Trans. 1 1981, 12.
13. The reactions and X-ray analyses were carried out using racemic material. The absolute stereochemistry depicted by the structures is relative to R* being (-)-TCC.
14. Trapping of the enolate (LiHMDS, THF, -78 °C) with TMSCl gave E/Z silyl enol ethers in a ratio of 3/97. For a discussion on the stereochemistry of enolate formation, see: Heathcock, C. H. In Asymmetric Synthesis; Morrison, J. D., Ed.; Academic Press: Orlando, FL, 1984; Vol. 3, Chapter 2, pp 111-206.
15. Fairbanks, A. J.; Sinay, P. Tetrahedron Lett. 1995, 36, 893.
16. An acyclic TS is proposed based on an apparent low-energy conformation that does not favor a chelate; however, some sort of chelation control cannot be ruled out at this time. This TS model suggests that due to steric interactions E-enolates should be more reactive than Z-enolates. This difference in reactivity may explain the high diastereoselectivity obtained on reaction of 1 with the zinc enolate of 3-pentanone (3 equiv) which is likely a 70/30 mixture of E and Z isomers.
17. Brown, D. S.; Earle, M. J.; Fairhurst, R. A.; Heaney, H.; Papageorgiou, G.; Wilkins, R. F.; Eyley, S. C. Synlett 1990, 619.
18. Murata, S.; Suzuki, M.; Noyori, R. Tetrahedron 1988, 44, 4259.
19. Morimoto, Y.; Nishida, K.; Hayashi, Y.; Shirahama, H. Tetrahedron Lett. 1993, 34, 5773.
20. For examples of prochiral enolate additions to imines, see: Kleinman, E. F. In Comprehensive Organic Synthesis; Trost, B. M., Ed.; Pergamon Press: Oxford, 1991; Vol. 2, p 893.
21. (a) Nahm, S.; Weinreb, S. M. Tetrahedron Lett. 1981, 22, 3815.
22. (b) Shimizu, T.; Osako, K.; Nakata, T. Tetrahedron Lett. 1997, 38, 2685 and references therein.