methyl 2-[(3S,4R)-4-chloro-3-[1-methyl-1-(4-nitrobenzyloxycarbonyloxy)ethyl]-2-oxoazetidin-1-yl]-3-methylbut-2-enoate 以70.0 mg (18.9%)的产率得到methyl 3-methyl-2-[(3S,4R)-3-[1-methyl-1-(4-nitrobenzyloxycarbonyloxy)ethyl]-4-[2-(4-nitrobenzyloxycarbonyl-methyl)allyl]-2-oxoazetidin-1-yl]but-2-enoate