Remarkable Lewis acid mediated enhancement of enantioselectivity during free-radical reductions by simple chiral non-racemic stannanes

Abstract

Additions of 1 equiv. of achiral and chiral Lewis acidsto free-radical reduction reactions involving (1S,2S,5R)-menthyldiphenyltin hydride 1, bis[(1S,2S,5R)-menthyl]-phenyltin hydride 2, bis[1S,2S,5R)-menthyl][8-(N,N-dimethylamino)naphthyl]tin hydride 3, bis[(1R,2S,5R-menthyl]{1-(S)-N,N-dimethylaminoethyl]phenyl}tin hydride 4 or 3α-dimethylstannyl-5α-cholestane 5 result in remarkable increases in enantioselectivity.

References

1. For excellent reviews, see: D. P. Curran, N. A. Porter and B. Giese, Stereochemistry of Radical Reactions, VCH, Weinheim, 1995; W. Smadja, Synlett., 1994, 1; N. A. Porter, B. Giese and D. P. Curran, Acc. Chem. Res., 1991, 24, 296.
2. M. Sibi and N. A. Porter, Acc. Chem. Res., 1999, 32, 163.
3. For early examples, see: Y. Guindon, K. Yoakim, R. Lemieux, L. Boisvert, D. Delorme and J.-F. Lavellée, Tetrahedron Lett., 1990, 31, 2845; Y. Guindon, J.-F. Lavallée, M. Llinas-Brunet, G. Horner and J. Rancourt, J. Am. Chem. Soc., 1991, 113, 9701.
4. For a comprehensive review, see: P. Renaud and M. Gerster, Angew. Chem., Int. Ed., 1998, 37, 2563.
5. H. Schumann, B. Pachaly and B. C. Schütze, J. Organomet. Chem., 1984, 265, 145.
6. D. P. Curran and D. Nanni, Tetrahedron: Asymmetry, 1996, 7, 2417.
7. M. Blumenstein, K. Schwartzkopf and J. O. Metzger, Angew. Chem., Int. Ed. Engl., 1997, 36, 235.
8. K. Schwartzkopf, M. Blumenstein, A. Hayen and J. O. Metzger, Eur. J. Chem., 1998, 177.
9. D. Dakternieks, K. Dunn, D. J. Henry, C. H. Schiesser and E. R. T. Tiekink, Organometallics, in press; C. H. Schiesser and M. A. Skidmore, Phosphorus Sulfur Silicon Relat. Elem., in press.
10. J. B. T. H. Jastrzebski, G. van Koten, K. Goubitz, C. Arlen and M. Pfeffer, J. Organomet. Chem., 1983, 246, C75; G. van Koten and J. B. T. H. Jastrzebski, Tetrahedron, 1989, 45, 569.
11. V. T. Perchyonok and C. H. Schiesser, Tetrahedron Lett., 1998, 39, 5437.
12. A. Campbell and S. Kenyon, J. Chem. Soc., 1946, 25; C. Aaron, D. Dull, S. L. Schmiegel, D. Jaeger, J. Ohashi and H. S. Mosher, J. Org. Chem., 1967, 32, 2797; F. A. A. Elhafez and D. J. Cram, J. Am. Chem. Soc., 1952, 74, 5846.
13. Jacobson's catalyst: E. N. Jacobsen, W. Zhang, A. R. Muci, J. R. Ecker and L. Deng, J. Am. Chem. Soc., 1991, 113, 7063.
14. M. Murakata, H. Tsutsui and O. Hoshino, J. Chem. Soc., Chem. Commun., 1995, 481.
15. M. Murakata, T. Jono, Y. Mizuno and O. Hoshino, J. Am. Chem. Soc., 1997, 119, 11 713.
16. M. B. Haque, B. P. Roberts and D. A. Tocher, J. Chem. Soc., Perkin Trans. 2, 1998, 2881.
17. D. Dakternieks, D. J. Henry and C. H. Schiesser, J. Phys. Org. Chem., 1999, 12, 233.