β-branched α-halo carboxylic acid derivatives via stereoselective 1,4 addition of dialkylaluminum chlorides to α,β -unsaturated n-acyloxazolidinones

摘要

The stereoselevtive synthesis of β-branched α-halo carboxylic acids containing two newly formed chiral centers is accomplished by a reaction cascade consisting of the 1,4 addition of dialkylaluminum chlorides to α,β-unsaturated N-acyloxazolidinones and subsequent reaction of the intermediate aluminum enolates with N-halosuccinimide. The most efficient sttereocontrol in these tandem processes has been achieved with oxazolidinones derived from glucosamine.