1,5-Dimethyl-6H-pyridazino[4,5-b]carbazole, a 3-aza bioisoster of the antitumor alkaloid olivacine

Abstract

A series of b-fused carbazoles structurally related to pyrido[4,3-b] carbazole-type alkaloids was prepared, utilizing the Diels-Alder reaction of 1-methylpyrano[3,4-b]indol-3(9H)-one with electron-deficient acetylenic dienophiles as the key step. The title compound (14) thus obtained in only four steps represents a new 3-aza analog of the antitumor natural product, olivacine. © 2002 Pharmaceutical Society of Japan.