Nicotine chemistry : The addition of organolithium reagents to (—)-nicotine

Organolithium reagents (RLi; where R = ethyl, isopropyl,cyclopropyl,n-butyl, sec-butyl, t-butyl, vinyl) have been found to add regiospecifically to (—)-nicotine to provide a series of 6-substituted nicotinoids of low optical activity. The data presented for the organolithium additions coupled with an analysis of the addition oft-BuLi to(—)-nicotine and [2'-²H]nicotine have provided strong evidence for a novel racemization process caused by pyrrolidine ring-opening and reclosure involving nicotine's N'—C'₂ bond.