Total synthesis of maytansinoids. Approach to 4,6-bisdemethylmaytansine and 4-demethylmaytansine

A convergent strategy was elaborated to synthesize maytansine 1 and maytansinoids modified on the carbon skeleton, especially 4-demethylmaytansine 2, 6-demethylmaytansine 3, 4,6-bisdemethylmaytansine 4. In this paper, the feasibility of the project was verified by the preparation of key intermediates for the synthesis of 4, 6-bisdemethylmaytansine and 6-demethylmaytansine. The C-1-N open chain compound 18 in the 4,6-bisdemethyl series was obtained.