seven chiral azolinium and five functionalized chiral azolinium salts, precursors to N-heterocyclic carbenes, derived from l-proline has been developed. Moderate to good overall yields were obtained. Some NHC dimers and thiones were isolated. X-ray crystal structure determinations of two [Rh-NHC] complexes were also reported. A short and flexible procedure for the preparation of seven chiral azolinium
Enantioselective conjugate addition of ketones to β-nitrostyrenes catalyzed by 1,2-amino alcohol-derived prolinamides
作者:Diana Almaşi、Diego A. Alonso、Carmen Nájera
DOI:10.1016/j.tetasy.2006.07.023
日期:2006.8
Various L-prolinamides 14, prepared from L-proline and chiral beta-amino alcohols, are active bifunctional catalysts for the direct nitro-Michael addition of ketones to beta-nitrostyrenes. In particular, catalyst 14e prepared from L-proline and (1S,2R)-cis-1amino-2-indanol exhibits the highest catalytic performance working in polar aprotic solvents such as NMP. High syn-diastereoselectivities (up to 94% de) and good enantioselectivities (up to 80% ee) were obtained at rt. (c) 2006 Elsevier Ltd. All rights reserved.