acid-washed silica gel 、 α-(2-carbo-tert.-butyloxy-3,3-dimethyl-7-oxo-4-thia-2,6-diaza-6-bicyclo [3,2,0]heptyl)-α-(triphenylphosphoranylidene)-acetic acid 2,2,2-trichloroethyl ester 、
tert-butyl glyoxylate 生成
α-(2-carbo-tert.-butyloxy-3,3-dimethyl-7-oxo-4-thia-2,6-diaza-6-bicyclo[3,2,0]heptyl)-α-(carbo-tert.-butyloxy-methylene)-acetic acid 2,2,2-trichloroethyl ester