Stereoselective Synthesis of New Podophyllotoxin Derivative: 4-cyano-4-deoxy-4-demethylepipodophyllotoxin

Podophyllotoxin(1), which shows high antitumor activity, is isolated from Podophyllum pelatum L. or Podophyllum emodi L.. But, because of its serious side-effect, it cannot be used as antitumor agent clinically. Its semisynthetic derivatives, Etoposide(2) and Teniposide(3), are wide-used, important anticancer drugs[1] (Chart 1). However, they have several limitations such as poor water solubility, metabolic inactivation and development of drug resistance. To overcome these limitations, many derivatives of podophyllotoxin have been synthesized in many laboratories[2]. It has been recognized thatßsubstitution at C-4 position is necessary to the compounds with high activity. Our group has established a methodology to synthesize 4-b -substituted derivative of podophyllotoxin stereoselectively[2b]. This communication report the synthesis of 4-b -cyano-4-deoxy-4’-demethylepipodophyllotoxin, which is a important intermediate for synthesizing 4-b -carbon subtituted derivative.