Highly diastereoselective hydrosilation reactions. Spirocyclic siloxanes: Sources of Si-based Lewis acids

Tetrahedron Letters

Volumn 37, Issue 6, 1996, Pages 827-830

  Young, David G J ^a   Hale, Michael R ^a   Hoveyda, Amir H ^a  

^a BOSTON COLLEGE   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

SILANE DERIVATIVE;

ARTICLE; DRUG SYNTHESIS; REACTION ANALYSIS; STEREOCHEMISTRY;

EID: 0030039487     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/0040-4039(95)02332-1     Document Type: Article

References (14)

1. (a) Myers, A. G.; Kephart, S. E.; Chen, H. J. Am. Chem. Soc. 1992, 114, 7922-2923.
2. (b) Denmark, S. E.; Griedel, B. D.; Coe, D. M.; Schnute, M. E. J. Am. Chem. Soc. 1994, 116, 7026-7043 and references cited therein.
3. Hale, M. R.; Hoveyda, A. H. J. Org. Chem. 1992, 57, 1643-1645.
4. Tamao, K.; Nakajima, T.; Sumiya, R.; Arai, H.; Higuchi, N.; Ito, Y. J. Am. Chem. Soc. 1986, 108, 6090-6093.
5. (b) Tamao, K.; Tanak, T.; Nakajima, T.; Sumiya, K.; Arai, H.; Ito, Y. Tetrahedron Lett. 1986, 27, 3377-3380.
6. Bergens, S. H.; Noheda, P.; Whelan, J.; Bosnich, B. J. Am. Chem. Soc. 1992, 114, 2121-2128.
7. The reason for this enhancement in stereoselectivity is not clear at present and must await the outcome of ongoing mechanistic studies.
8. 4Si: C, 57.32; H, 8.88. Found: C, 57.47; H, 8.82.
9. 29Si NMR data, see: Brey, S. W. In Petrarch Systems Catalogue 1987, pp 60-68. equation presented
10. Hale, M. R.; Hoveyda, A. H. J. Org. Chem. 1994, 59, 4370-4374.
11. Westheimer, F. H. Acc. Chem. Res. 1968, 1, 70-78 and references cited therein.
12. For X-ray structures of spirocyclic disiloxanes and their derived hypervalent derivatives, see: Stevenson, W. H.; Wilson, S.; Martin, J. C.; Farnham, W. B. J. Am. Chem. Soc. 1985, 107, 6340-6352. In the tetravalent and hypervalent (trigonal bipyramidal systems) the bond angle at the Si is 94° and 85°, respectively.
13. Ring strain may be due to longer C-Si bond lengths. If Si were to adopt the expected 109° angle, the two carbon sites (C-Si) would have to be stretched apart, causing torsional strain. To avoid strain, the bond angle at Si is smaller than expected for a tetrahedral structure.
14. Both 11 and 17 also contain a siloxy ring; these compounds have less of a tendency to adopt a trigonal bipyramidal structure probably because 13 possesses an additional ring system which enhances ring strain. Formation of the derived hydrate is not favored with 8, probably because of an α-Me substituent.