4,24-Dioxa-9,22-diazatetracyclo[19.3.1.110,14.03,5]hexacosane, maytansine deriv. 72902-38-6 ANSAMITOCIN DERIV Maytansine, 2'-de(acetylmethylamino)-O(20)-demethyl-2'-methyl- Maytansine, 2'-de(acetylmethylamino)-O20-demethyl-2'-methyl- NSC314018 TN-006