4-(4-(3-cyano-4-(ethylsulfonyl)phenylamino)-4-oxobutyl)phenylboronic acid 、
(R,E)-ethyl 3-(benzyloxycarbonylamino)-3-(3-(4-(4-bromo-2,6-dimethylphenyl)but-2-enamido)phenyl)propanoate 、 以to give 53E (775 mg, 82%) as a yellow powder的产率得到(R,E)-4-(4-(3-(1-(benzyloxycarbonylamino)-3-ethoxy-3-oxopropyl)phenylamino)-4-oxobut-2-enyl)-3,5-dimethylphenylboronic acid