3-t-butoxycarbonylamino-2-(4-thioureidophenyl)propionic acid methyl ester 、
碘乙烷 以the same procedure of Example 29 gave 0.55 g of the titled compound (yield, 96%)的产率得到3-t-butoxycarbonylamino-2-(4-(S-ethylisothioureido)phenyl)propionic acid methyl ester