Metal–ammonia reduction of aromatic nitrogen heterocycles. Part I. Reductive alkylation of quinoline and some methyl derivatives

Abstract

Reductive alkylation of quinoline with lithium and various alkylating agents in liquid ammonia affords exclusively 1-alkyl-1,4-dihydroquinolines. Quinolines substituted with Me in the 2-, 3-, 4-, or 8-positions behave similarly but the 1,2-dimethyl product is partly transformed into an exocyclic double bond isomer upon distillation. The structures of the reduction products have been established by spectroscopic and chemical methods and aspects of the mechanism of formation have been elucidated.