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 bromoacety l substituent at position 3, with N,N-dimethylguanidine is reported. I n general, 5-indol-3-yl imidazole derivatives are found to be the reac tion products, however when the 3-bromoacetyl-2-tertbutoxycarbonylamin oindole is used the hylamino4-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 analysi s. The water molecules in 5. H2O act as both donor (O-H...N) and accep tor (N-H...O) and are responsible for the formation of strands along t he b axis. (C) 1998 Elsevier Science Ltd. All rights reserved.