Hexahydropyrrolo[2,3-b]indole alkaloids of biological relevance: proposed biosynthesis and synthetic approaches

Abstract

The hexahydropyrrolo[2,3-b]indole alkaloids represent a diverse family of structurally complex tryptamine derived alkaloids isolated from a widespread series of natural sources. A hexahydropyrrolo[2,3-b]indole ring having a carbon substituent at C-3a is the defining structural feature of a diverse collection of natural products. The structural complexity of the hexahydropyrrolo[2,3-b]indole alkaloids makes them a particularly elusive and at the same time, appealing target for total synthetic effort. In this review article, we discuss on the biosynthetic proposal as well as key efforts on the total syntheses of naturally occurring complex hexahydropyrrolo[2,3-b]indole alkaloids.