4,24-Dioxa-9,22-diazatetracyclo[19.3.1.110,14.03,5]hexacosane, maytansine deriv. (ZCI); Maysanine,(14S,16S,32S,33S,2R,4S,10E,12E,14R)-86-chloro-14-hydroxy-85,14-dimethoxy-33,2,7,10-tetramethyl-12,6-dioxo-7-aza-1(6,4)-oxazinana-3(2,3)-oxirana-8(1,3)-benzenacyclotetradecaphane-10,12-dien-4-yl N-acetyl-N-methyl-L-alaninate,Maytansine