An Efficient Synthesis of C-11 Substituted 6H-PyridoCarbazoles

Article abstract of DOI:10.1016/S0040-4020(01)82308-5

A synthesis of the natural product 5-methyl-6H-pyrido<4,3-b>carbazole-11-methanol, 5 from the ketolactam 7 is described.Compound 7 was treated with one equivalent of MeLi followed by quenching of the reaction mixture with water to give the lactone 19.Compound 19 was treated with a number of organolithium reagents such as methyllithium, n-butyllithium, ethoxyvinyl lithium and the lithio derivative of formaldehyde diethyl mercaptal to give, after sodium borohydride reduction, 1, 15, 30, and 31 respectively.Compounds 30 and 31 were hydrolyzed and then reduced to give compounds 5 and 6 respectively, in an overall yield of 21percent.Compounds 16 and 22 were identified as the intermediates in the Saulnier-Gribble synthesis of ellipticine. Key Words: Ellipticine; 9-Methoxy-ellipticine; Pyrido<4,3-b>Carbazole; Natural Product; Antitumor Agents