5
c-cyclopropyl-5
t-methyl-2-thioxo-oxazolidine-3,4
r-dicarboxylic acid 3-benzyl ester 4-ethyl ester 、 3-O-benzyl 4-O-ethyl (4S,5R)-5-cyclopropyl-5-methyl-2-sulfanylidene-1,3-oxazolidine-3,4-dicarboxylate 、
potassium tert-butylate 生成
(E)-2-Benzyloxycarbonylamino-3-cyclopropyl-but-2-enoic acid ethyl ester