complexes were highly efficient catalysts for asymmetrichydrogenation of β-aryl-substituted β-(acylamino)acrylates and β-aryl-substituted β-keto esters. The Ru-bisphosphinite catalysts can tolerate an E/Z mixture of β-aryl-substituted β-(acylamino)acrylates. These highly enantioselective hydrogenations provide a useful way to prepare β-aryl-substituted β-amino acids and β-hydroxyl acids.
A highlyefficient and enantioselective hydrogenation of unprotected β-enamine esters catalyzed by Ir-(S,S)-f-Binaphane complex has been developed. This methodology provides straightforward access to free β-amino acids in high yields with excellent enantioselectivities up to 97% ee and high reactivities (TON > 5000).
Chiral 1-phenylethylamine-derived phosphine-phosphoramidite ligands for highly enantioselective Rh-catalyzed hydrogenation of β-(acylamino)acrylates: significant effect of substituents on 3,3′-positions of binaphthyl moiety
A series of new chiral phosphine-phosphoramidite ligands with a 3,3′-substituted binaphthyl moiety were prepared from 1-phenylethylamine, and successfully applied in the Rh-catalyzed asymmetrichydrogenation of β-(acylamino)acrylates. The research disclosed that the substituents on the 3,3′-positions of binaphthyl moiety significantly influenced the enantioselectivity.
Highly Efficient Synthesis of Chiral β-Amino Acid Derivatives via Asymmetric Hydrogenation
作者:Wenjun Tang、Xumu Zhang
DOI:10.1021/ol026935x
日期:2002.11.1
The Rh-TangPhos complex is an efficient hydrogenation catalyst for making chiral beta-amino acid derivatives. With the Rh-TangPhos system, high enantioselectivities (up to 99.6%) and turnover numbers have been obtained in the hydrogenation of E/Z isomeric mixtures of both beta-alkyl and beta-aryl beta-(acylamino)acrylates. [reaction: see text]