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

Abstract

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 reduction–oxidation protocol using a combination of NaBH 4 and Pd–C on MgSO 4 ·7H 2 O, 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.