REVERSAL OF STEREOSELECTIVITY IN THE EVANS ALDOL REACTION OF ALPHA,ALPHA-DIFLUORO AND ALPHA,ALPHA,ALPHA-TRIFLUORO CARBONYL-COMPOUNDS

Authors
ISEKI K OISHI S KOBAYASHI Y
Citation
K. Iseki et al., REVERSAL OF STEREOSELECTIVITY IN THE EVANS ALDOL REACTION OF ALPHA,ALPHA-DIFLUORO AND ALPHA,ALPHA,ALPHA-TRIFLUORO CARBONYL-COMPOUNDS, Tetrahedron, 52(1), 1996, pp. 71-84
Citations number
36
Categorie Soggetti
Chemistry Inorganic & Nuclear
Journal title
Tetrahedron → ACNP
ISSN journal
00404020
Volume
52
Issue
1
Year of publication
1996
Pages
71 - 84
Database
ISI
SICI code
0040-4020(1996)52:1<71:ROSITE>2.0.ZU;2-8
Abstract
The Evans aldol reaction of hexafluoroacetone and trifluoroacetaldehyd e causes complete reversal of diastereofacial selectivity. The boron e nolate derived from N-acyloxazolidinone 2 reacts with trifluoroacetald ehyde to give anti and ''non-Evans'' syn aldols with stereoselectivity in the range of 7:3-17:3. With alpha,alpha-difluoroaldehyde 4b, a sma ll amount of the normal syn aldol was formed. However, the anti aldol was the major product.