NEW MATERIAL:The compound of formulaI(X is H, alkyl or acyl; Y is H or Cl; R is H or acyl derived from carboxylic acid).

EXAMPLE: 4,5-Deoxymaytansinol.

USE: An antitumor agent and antimicrobial agent. It exhibits strong mitotic division inhibiting action and antitumor action, and nevertheless, is low toxic. It has also antifungal and antiprotozoal activities, and is useful for the examination of activated sludge, treatment of plant diseases, etc.

PROCESS: The compound of formulaIis prepared, e.g. by the deoxidation of the compound of formula II. The reaction is carried out e.g. in the presence of a metal or a halide of a metal having low valency (pref. Ti or Zn-Cu complex), pref. in a solvent such as THF at -70W+150°C.