Abstract
p-Nitrophenylserine butyl ester when reduced with calcium borohydride, gave a compound which could have had structure A, B, or C. Spectropolarimetric, IR and NMR evidence indicated structure IV, a calcium boroxazolidine related to A. A zwitterionic boroxazolidine II was synthesized from threo-1-
p-nitrophenyl-2-aminopropane-1,3-diol and ethyl borate.