Heteroatom directed photoannulation: synthesis of indoloquinoline alkaloids: cryptolepine, cryptotackieine, cryptosanguinolentine, and their methyl derivatives

A three-step synthesis of indoloquinoline alkaloids is described. The reaction of 2,3 and 4-substituted haloquinolines with anilines afforded the respective anilinoquinolines, which upon photocyclization gave the indoloquinolines. By regioselective methylation on quinoline nitrogen, fumished the alkaloids cryptotackieine, cryptosanguinolentine, cryptolepine, and the synthetic isomer isoneocryptolepine. Their methyl derivatives were also synthesized in search of new antiplasmodial drugs and DNA intercalating agents. (c) 2006 Elsevier Ltd. All rights reserved.