Regioselectivity in the Lithiation of 1,3-Disubstituted Arenes

Abstract

The regioselectivity of the lithiation of 1,4,5,8-tetramethoxynaphthalene-2-carbaldehyde (7) with butyllithium or phenyllithium in the presence of N,N,N′-trimethylethylenediamine and the subsequent bromination of the lithiated species so generated with 1,2-dibromotetrafluoroethane were investigated. Similar investigations with butyllithium as base in the presence of N,N,N′,N′-tetramethylethylenediamine or potassium t-butoxide were carried out on 1,4,5,8-tetramethoxynaphthalene-2-methanol (14). These studies were extended to 1,5,8-trimethoxynaphthalene-3-methanol (25), 3-methoxybenzenemethanol (29) and 3,5-dimethoxybenzenemethanol (32). The X-ray crystal structure of 6-bromo-1,4,5,8-tetramethoxynaphthalene-2-methanol (17) is described.