Short synthesis of carbazole alkaloids: Ekeberginine, murrayaquinone A, and glycozoline

ABSTRACTThree differently substituted, naturally occurring, biologically active carbazole derivatives (viz. ekeberginine, murrayaquinone A, and glycozoline) were synthesized in good yield using short and simple routes. The prenyl group was selectively introduced at the C4 position using a Stille coupling reaction in the synthesis of ekeberginine. Murrayaquinone A was synthesized using Raney nickel–mediated desulfurization of dithiane as a key step. Synthesis of glycozoline was achieved in two steps from 3-methyl carbazole via an intermediate 3-bromo-6-methyl carbazole.