Investigative studies on the formation of the imidazo [4′,5′:3,4]pyrido[2,3-b]indole ring:: Formal synthesis of the alkaloids grossularines-1 and 2.: X-ray crystal structures of 5-indol-3-yl-imidazole and bisimidazocarbazole derivatives.

Reactions of several 2,3-disubstituted indoles, bearing a chlorine or amino function at position 2 and an 1,2-dicarbonyl group or bromoacetyl substituent at position 3, with N,N-dimethylguanidine is reported. In general, 5-indol-3-yl imidazole derivatives are found to be the reaction products, however when the 3-bromoacetyl-2-tertbutoxycarbonylaminoindole is used the 2-dimethylamino4-hydroxy-6-methoxymethyl-3H-imidazo[4',5' :3,4]pyrido[2,3-b]indole is obtained through a step-wise formation of the pyridine and the imidazole rings. The crystal molecular structure of 5.H2O and 7.HBr.H2O.3/2 EtOH have been determined by X-Ray analysis. The water molecules in 5. H2O act as both donor (O-H...N) and acceptor (N-H...O) and are responsible for the formation of strands along the b axis. (C) 1998 Elsevier Science Ltd. All rights reserved.