Stereocontrolled synthesis of enantiopure cis- and trans-3,4,4a,5,8,8a-hexahydro-1 H-quinolin-2-ones

Abstract

Starting from the 8-allyl substituted oxazolopiperidone lactam 2b, which is easily accessible from ( R)-phenylglycinol and racemic δ-oxoester 1a, two-step sequences involving a stereoselective α-amidoalkylation reaction, either with inversion or retention of configuration, followed by a ring-closing metathesis, provide diastereodivergent routes to enantiopure cis- and trans-3,4,4a,5,8,8a-hexahydro-1 H-quinolin-2-ones.