NEW CHIRAL ALANINE TEMPLATE WITH A 1,2,3,6-TETRAHYDRO-2-PYRAZINONE STRUCTURE FOR THE ASYMMETRIC-SYNTHESIS OF ALPHA-METHYL ALPHA-AMINO-ACIDS

sopropyl-5-phenyl-1,2,3,6-tetrahydro-2-pyrazinone, prepared from (R)-v aline and (S)-alanine, reacts with activated alkyl halides and electro philic olefins under solid-liquid PTC conditions with K2CO3 as base, a t room temperature and with high diastereoselectivity (>94%). The pall adium-catalyzed allylation reaction of this alanine derivative under n eutral conditions at room temperature also takes place with a de>96%. Final hydrolysis of alkylated pyrazinones affords enantiomerically :pu re alpha-methyl alpha-amino acids. (C) 1998 Elsevier Science Ltd. All rights reserved.