The differentially protected 2-thiazolyl amino ketones 3 and 7 obtained in high yield from the L-threonine derived methyl ester 2 and 2-lithiothiazole serve as key intermediates to aldehydes 6 and 11 by syn- and anti-stereoselective reduction (diastereoselectivity 95%) of the carbonyl and liberation of the formyl group from the thiazole ring; the latter compounds are smoothly oxidized to acids 12 and 13.