Asymmetric synthesis of all isomers of alpha-methyl-beta-phenylserine

This report describes the synthesis of enantiomerically pure (2R,3R)-, (2R, 3S)-, (2S,3S)- and (2S,3R)-2-amino-3-hydroxy-2-methyl-3-phenylpropanoic aci ds, four quaternary a-amino acids, using a stereodivergent synthetic route and starting from (S)- and (R)-N-Boc-N,O-isopropylidene-alpha-methylserinal s The key step involves the asymmetric Grignard additions to the above chir al aldehydes, in which high levels of asymmetric induction are observed. (C ) 2000 Elsevier Science Ltd. All rights reserved.