cryptophycin 226

2-[5-[2-(3-tert-butoxycarbonylamino-2-methyl-propionyloxy)-4-methyl-pentanoylamino]-8-(tert-butyl-dimethyl-silanyloxy)-7-hydroxy-6-methyl-8-phenyl-oct-2-enoylamino]-3-(3-chloro-4-methoxy-phenyl)-propionic acid 2,2,2-trichloro-ethyl ester