Interactions of 4-isopropylpyridine with organolithium reagents and lithium aluminium hydride: unusual electrophilic substitutions

Abstract

Products from the interaction of several organolithium reagents with 4-isopropylpyridine have been shown by 1H n.m.r. to be σ-complexes and-or N-lithio-dihydropyridines. Treatment of the σ-complex from 4-isopropylpyridine and t-butyl-lithium with benzyl chloride affords new tri- and di-substituted pyridines. The reaction of lithium aluminium hydride with 4-isopropylpyridine, followed by treatment with electrophilic reagents, leads to side-chain rather than ring substitution. Spectral evidence is presented for the intermediacy of an N-lithio-species.