Synthesis of Optically Pure Clausenamine-A and its Demethoxylated Analogs

The first total synthesis of Clausenamine-A (3) was developed involving the Suzuki cross-coupling and oxidative coupling reaction. The synthesis of its demethoxylated analogs 1 and 2 were also reported. Resolution of (+)-1, (+)-2, (+)-3 and (−)-1, (−)-2, (−)-3 were performed via their corresponding camphorsulfonates of the racemates. The absolute configurations of (+)-1, (+)-2, (+)-3 and (−)-1, (−)-2, (−)-3 were assigned as (aR) and (aS), respectively, by X-ray analysis and their CD spectrum. The primarily cytotoxic activities of these biscarbazoles against Plasmodium falciparum were briefly described.