Tandem asymmetric transformations: An asymmetric 1,2-migration from a higher order zincate coupled with a stereoselective homoaldol reaction

Journal of the American Chemical Society

Volumn 118, Issue 47, 1996, Pages 11970-11971

  McWilliams, J Christopher ^a   Armstrong III, Joseph D ^a   Zheng, Nan ^a   Bhupathy, M ^a   Volante, R P ^a   Reider, Paul J ^a  

^a MERCK RESEARCH LABORATORIES   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

INDAN DERIVATIVE; KETONE;

ARTICLE; CATALYSIS; DRUG SYNTHESIS; REACTION ANALYSIS; STEREOCHEMISTRY;

EID: 0029902454     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja962123i     Document Type: Article

References (25)

1. (a) Noyori, R. Asymmetric Catalysis in Organic Synthesis; John Wiley & Sons. Inc.: New York, 1994.
2. (b) Wong, C.-H; Whitesides, G. M. Enzymes in Synthetic Organic Chemistry, Tetrahedron Organic Chemistry Series; Pergamon Press: Tarrytown, NY, 1994; Vol. 12.
3. (a) Armstrong, J. D., III; Hartner, F. W., Jr.; DeCamp, A. E.; Volante, R. P.; Shinkai, I. Tetrahedron Lett. 1992, 33, 6599. See also:
4. (b) DeCamp, A. E.; Kawaguchi, A. T.; Volante. R. P.; Shinkai, I. Tetrahedron Lett. 1991, 32, 1867.
5. (c) Reetz, M. R.; Karin, R.; Griebenow, N. Tetrahedron Lett. 1994, 35, 1969.
6. (d) Reetz, T. R.; Fox, D. N. A.; Tetrahedron Lett. 1993, 34, 1119.
7. (e) Reetz, M. R. Angew. Chem., Int. Ed. Engl. 1991, 30, 1531.
8. (f) Kano, S.; Yokomatsu, T.; Shibuya, S. Tetrahedron Lett. 1991, 32, 233.
9. The first step in the sequence is a non-stereoselective aldol between 7 and formaldehyde.
10. (a) Sidduri, A.; Rozema, M. J.; Knochel, P. J. Org. Chem. 1993, 58, 2694 and references cited therein,
11. (b) Knochel, P.; Singer, R. D. Chem. Rev. 1993, 93, 2117. For an early example of the use of a zinc carbenoid with a lithium enolate, see:
12. (c) Whitlick, H. W., Jr.; Overman. L. E. J. Org. Chem. 1969, 34, 1962.
13. 2Zn → 7 + 2EtI. For preparation of 8, see ref 4a and Supporting Information.
14. -1, respectively) are observed with the disappearance of the lithium enolate absorbances.
15. The assignment of a carbon-bound (as opposed to oxygen-bound) zincate species for 11 is based upon low-temperature NMR observations. Enolate zincate 11 is drawn as a monomer for clarity. Prior stuctural studies on zinc enolates suggest 11 may exist in aggregate forms through dative Zn-C or Zn-O bonding. For related examples, see: (a) Bolm, C.; Müller, J.; Zehnder, M.; Neuburger, M. A. Chem. Eur. J. 1995, 1, 312 and references sited therein. (b) Fabicao, R. M.; Pajerski, A. D.; Richey, G. H., Jr.; J. Am. Chem. Soc. 1991, 113, 6680.
16. The assignment of a carbon-bound (as opposed to oxygen-bound) zincate species for 11 is based upon low-temperature NMR observations. Enolate zincate 11 is drawn as a monomer for clarity. Prior stuctural studies on zinc enolates suggest 11 may exist in aggregate forms through dative Zn-C or Zn-O bonding. For related examples, see: (a) Bolm, C.; Müller, J.; Zehnder, M.; Neuburger, M. A. Chem. Eur. J. 1995, 1, 312 and references sited therein. (b) Fabicao, R. M.; Pajerski, A. D.; Richey, G. H., Jr.; J. Am. Chem. Soc. 1991, 113, 6680.
17. The involvement of higher order zincates in 1.2-migrations has been previously implicated: Harada, T.; Katsuhira, T.; Hattori, K.; Oku, A. J. Org. Chem. 1993, 58, 2958.
18. Although implied as a short-lived intermediate in Scheme 3, 12a may exist only as a transition state structure.
19. For migrations of halogen-substituted triorganozincates, see: Harada, T.; Wada, H.: Oku, A. J. Org. Chem. 1995, 60, 5370 and references cited therein.
20. 2OLi, 31). Low conversions for the dialkoxide and lithium ethoxide likely reflects the limited solubility of these species at - 70°C. Low temperatures and inverse addition of 7 to 8 (thereby preventing free lithium enolate 7 attack on ethyl iodide) are necessary to minimize formation of 10 (typically, 3-6% of 10 is still observed).
21. -1. (13) Ratios were determined by GLC analysis (experimental details are described in the Supporting Information).
22. Only the homoaldol product 4a was detected in the crude mixture (HPLC).
23. For a recent example of diastereoselective homoaldol reactions of zinc homoenolates, see: (a) Houkawa, T.; Ueda, T.; Sakami, S.; Asaoka, M.; Takei, H. Tetrahedron Lett. 1996, 37, 1045. See also: (b) Nakamura, E.; Oshino, H.; Kuwajima, I. J. Am. Chem. Soc. 1986, 108, 3745.
24. For a recent example of diastereoselective homoaldol reactions of zinc homoenolates, see: (a) Houkawa, T.; Ueda, T.; Sakami, S.; Asaoka, M.; Takei, H. Tetrahedron Lett. 1996, 37, 1045. See also: (b) Nakamura, E.; Oshino, H.; Kuwajima, I. J. Am. Chem. Soc. 1986, 108, 3745.
25. The stereoselectivity of the homoaldol reaction was determined by transformation to the lactones (vide infra) and examination of coupling constants and NOE effects.