A Tandem Reduction-Oxidation Protocol for the Conversion of 1-Keto-1,2,3,4-tetrahydrocarbazoles to Carbazoles via Tosylhydrazones through Microwave Assistance: Efficient Synthesis of Glycozoline, Clausenalene, Glycozolicine, and Deoxycarbazomycin B and the Total Synthesis of Murrayafoline A

A novel and efficient methodology for the synthesis of carbazoles from 1-keto-1,2,3,4-tetrahydrocarbazoles via the corresponding tosylsulfonhydrazones by a one-pot tandem reductionoxidation protocol using a combination of NaBH4 and PdC on MgSO4 center dot 7H2O, a solid support, under microwave is developed. The reaction is successfully extended toward the synthesis of several naturally occurring carbazole alkaloids, namely 3-methylcarbazole, glycozoline, clausenalene, glycozolicine, murrayafoline A, and deoxycarbazomycin B, a carbazole derivative that is known to have a promising antimicrobial activity.