Synthesis of some hexahydroazocino[4,3-b]indoles, a tetra- and two hexahydropyrrolo[1′,2′ : 1,2]pyrrolo[3,4-b]indoles, and a tetrahydropyrrolo[2′,1′ : 5,1]imidazo[3,4-a]indole. Crystal structure determination of 1,2,3,4-tetrahydro-2-phenoxycarbonyl-7-phenylsulphonylazocino[4,3-b]indol-6 (5H)-one

Abstract

Hexahydroazocino[4,3-b]indoles (2a-c) have been synthesised from 1-phenylsulphonylindole by introducing the appropriate side chain at C-2, via lithiation, and then intramolecular Mannich cyclisation. From (2c), 1,2,3,4-tetrahydro-2-phenoxycarbonyl-7-phenylsulphonylazocino[4,3-b]indol-6(5H)-one (2e) was then prepared and its structure determined by the X-ray method; the benzyl group in (2c) was also replaced with other urethane groups. Cleavage, of the urethanes gave either a pyrrolo[1′2′ : 1,2]pyrrolo[3,4-b]indole or a 3-formyl-2-(4,5-dihydropyrrol-2-yl)indole. Reaction of 2-indol-2-ylpyrrolidine with formaldehyde in methanolic methoxide produced a pyrrolo[2′,1′ : 5,1]imidazo[3,4-a] indole.