Cyclization of o-(3-Hydroxy-3-methylbutynyl)phenols with Boron Tribromide to 4-Bromo-2,2-dimethylchromenes and Their Electroreduction to 2,2-Dimethylchromenes

Abstract

Cyclization of o-(3-hydroxy-3-methy1butynyl)phenols (2) with boron tribromide gave easily 4-bromo-2.2-dimethylchromenes(3).Electrolytic reduction of 3 at a Hg-pool electrode afforded the corresponding 2,2-dimethylchromenes (6) in high yields.