Chemical modification of herbimycin A. Synthesis and in vivo antitumor activities of halogenated and other related derivatives of herbimycin A.

Several halogenated and other related derivatives of herbimycin A have been synthesized and evaluated in vivo for their activities against Ehrlich ascites carcinoma. Some of these derivatives show higher activities than herbimycin A. Among them the derivatives modified at the 4, 5, 6, and 7-positions of the ansa chain showed particularly high activities.