A simple and general asymmetric synthesis of beta -amidophosphonates is described. The method involves the highly selective addition (up to 95% d.e.) of diethyl phosphite to various chiral alpha,beta -unsaturated carboxylic amides derived from chiral aminoalcohols. (C) 2001 Elsevier Science Ltd. All rights reserved.
Alternative synthesis of α-substituted β-amidophosphines by [1,4]-addition. A new route to chiral ligands
Phosphine-borane can be diastereoselectively added to chiral alpha,beta-unsaturated amides 3, using amino-alcohols as chiral inducers, leading to alpha-substituted beta-amidophosphine boranes 4 with up to 74% diastereomeric excess. Selective deprotection afforded optically pure carboxylic derivatives 5 which are key intermediates for the synthesis of various potential chiral ligands for asymmetric catalysis. (C) 2002 Published by Elsevier Science Ltd.