Studies on the asymmetric synthesis of pyrrolidine alkaloids and related compounds .1. Synthesis of a chiral precursor for preussin and AHPPA

Abstract

Starting from (S)-malic acid, the stereoselective synthesis of (4S, 5R)-1, 5-dibenzyl-4-benzyloxyl-2-pyrrolidone 9 by two methods was described, The key steps in the synthesis are two asymmetric alpha-amidoalkylation. The asymmetric alpha-amidoalkylation was easily achieved either from sulfone 7 by Ley's method or from 5 via an addition-reduction proceed io provide 9 in good (4/1 for 7) to excellent (97/3 for 5) trans stereoselectivity. Compound 9 is a chiral precursor for (-)- preussin and (3S, 4R)-4-amino-3-hydroxyl-5-phenylpentanoic acid(AHPPA).