A general asymmetric route to enantiomerically pure (S)-(+)-carnitine and analogs has been investigated that involves monoaddition of organometallic reagents to the lactone carbonyl group of (5R, 6S)-4-(benzyloxycarbonyl)-5, 6-diphenyl-2, 3, 5, 6-tetrahydro-4H-1, 4-oxazin-2- one and Lewis acid promoted stereoselective allylation of the resulting hemiacetals. The diastereomerically pure allyl oxazines thus obtained were readily converted into ...
