Synthesis of benzimidazoles containing a fused alicyclic ring by Rhodium - catalysed hydroformylation of N-alkenyl-1,2-diaminobenzenes

Abstract

Rhodium-catalysed reactions of N-alkenyl-1,2-diaminobenzenes(3) with hydrogen and carbon monoxide give benzimidazoles containing a fused alicyclic ring ((8) and (9)) in excellent yields. In some cases intermediate bicyclic compounds can be isolated and the 1H and 13C n.m.r. spectra of one of these, the 3,4,5,6-tetrahydro-4-methyl-3H-1,6-benzodiazocine (6), shows evidence for unusual atropisomerism.