6-{tert-butoxycarbonyl-[3-(4-cyano-benzyloxy)-5-formyl-2-methyl-pyridin-4-ylmethyl]-amino}-hexanoic acid 、
对氨基苯腈 以gave 6-(tert-butoxycarbonyl-{3-(4-cyano-benzyloxy)-5-[(4-cyano-phenylamino)-methyl]-2-methyl-pyridin-4-ylmethyl}-amino)-hexanoic acid (53) (0.9 g, 81% yield)的产率得到6-(tert-butoxycarbonyl-{3-(4-cyano-benzyloxy)-5-[(4-cyano-phenylamino)-methyl]-2-methyl-pyridin-4-ylmethyl}-amino)-hexanoic acid