Synthesis of 9-methylene-9,10-dihydroanthracene by lithium aluminium hydride reduction of (9-anthrylmethyl)trimethylammonium chloride

Abstract

Treatment of (9-anthrylmethyl) trimethylammonium chloride (2a) with 1 mol equiv. of lithium aluminium hydride (LAH) in refluxing tetrahydrofuran gave predominantly 9-methylene-9,10-dihydroanthracene (3a). However, reaction with 3 mol equiv. of LAH gave a mixture of 9-methyl-9,10-dihydroanthracene (5a) and 9-(9-anthrylmethyl)-9-methyl-9, 10-dihydroanthracene (6a), these products being formed by processes involving nucleophilic attack of excess of LAH on compound (3a).