Naphthopyrans by ring-closure of substituted naphthalenes using potassium t-butoxide in dimethylformamide
Abstract
Two 2-alkenyl-3-hydroxyalkyl-1,4-dimethoxynaphthalenes are cyclised with potassium t-butoxide in dimethylformamide to give 3-alkyl-3,4-dihydro-5,10-dimethoxynaphtho [2,3-c] pyrans under anaerobic conditions. One of these products is treated with the same solvent and base, but in air, to give the two possible 4-hydroxy derivatives.