New optically active 1,3-oxathiolanes

cis- and trans-5-Ethoxy-1,3-oxathiolane-2-carboxylic acids were obtained in pure form. The cis isomer was resolved into its enantiomers through diastereoisomeric salt formation with enantiomerically pure α-methylbenzylamine. Reduction of the salt followed by benzoylation led to 2-benzoyloxymethyl-5-ethoxy-2(R)-5(S)-1,3-oxathiolane and 2-benzoyloxymethyl-5-ethoxy-2(S)-5(R)-1,3-oxathiolane, useful intermediates in nucleoside chemistry. © 1993 Wiley-Liss, Inc.