4-[(2R,3R)-1-(tert-Butyl-dimethyl-silanyl)-3-ethyl-4-oxo-azetidin-2-yl]-3-oxo-butyric acid tert-butyl ester 、
N,N-二甲基甲酰胺二甲基缩醛 以87%的产率得到4-[(2R,3R)-1-(tert-Butyl-dimethyl-silanyl)-3-ethyl-4-oxo-azetidin-2-yl]-2-[1-dimethylamino-meth-(E)-ylidene]-3-oxo-butyric acid tert-butyl ester