A Novel Synthesis of 1‐Aryl‐9‐alkyl‐2, 3, 3a, 4, 9, 9a‐hexahydro‐1H‐pyrrolo[2, 3‐b] quinoxalines by lithium aluminium hydride reduction of N‐phenyl‐1‐benzimidazolyl‐succinimides

The N‐substituted 1‐benzimidazolyl‐succinimides 6a – v (Scheme 1, Table 1 and 2) have been prepared by the reaction of benzimidazole and its derivatives with maleimides. Reduction of the N‐cyclohexyl and N‐cyclo‐octyl substituted 1‐benzimidazolyl‐succinimides 6i – k with lithium aluminium hydride gives the normally expected substituted (N‐alkyl‐3‐pyrrolidinyl)benzimidazoles 14i – k . However by LiAlH 4 ‐reduction of the N‐phenyl substituted 1‐benzimidazolylsuccinimides 6a – h mainly the 1‐aryl‐9‐alkyl‐2, 3, 3a, 4, 9, 9a‐hexahydro‐1 H ‐pyrrolo[2, 3‐ b ]quinoxalines 7a – h are obtained. The mechanism of this unusual reduction has been elucidated.