Potential antitumor agents. III. Synthesis of pyrazolo[3,4‐e]pyrrolo[3,4‐g]indolizine and 1H‐pyrazolo[3,4‐e]indolizine derivatives

Abstract

AbstractThe preparation of 5‐dimethylaminoethyl‐4,6‐dioxo‐1‐phenyl‐1,4,5,6‐tetrahydropyrazolo[3,4‐e]pyrrolo‐[3,4‐g]indolizine, a derivative of the still unknown tetracyclic parent ring pyrazolo[3,4‐e]pyrrolo[3,4‐g]indolizine, is reported starting from 1‐phenyl‐5‐(1‐pyrryl)pyrazole‐4‐acetonitrile by PPA catalyzed double cyclization of the related oxalylcyanomethyl derivative and subsequent alkylation. The synthesis of 4,5‐bis(isopro‐pylaminocarbonyloxymethyl) and 4,5‐bis‐(cyclohexylaminocarbonyloxymethyl) derivatives of 1‐phenyl‐1H‐pyrazolo[3,4‐e]indolizine is also described. The new tricyclic and tetracyclic derivatives were tested as potential antitumor agents.