for the following products
(3R,4S)-1-tert-Boc-3-[(triethylsilyl)oxy]-4-phenyl-2-azatidinone | (3R,4S)-1-tert-Butoxycarbonyl-3-triethylsilyloxy-4-phenyl-2-azetidinone and (3R,4S)-1-Azetidinecarboxylic acid, 2-oxo-4-phenyl-3-[(triethylsily)oxy]-1,1-dimethylethyl ester
