A facile synthesis of isochromenes based on reactions of 2-lithio-β-methoxystyrenes with carbonyl compounds

The reactions of α-substituted 2-lithio-β-methoxystyrenes, generated in situ by bromine-lithium exchange between α-substituted 2-bromo-β-methoxystyrenes and butyllithium in diethyl ether at 0 °C, with carbonyl compounds afforded α-substituted 2-(β-methoxyvinyl)benzyl alcohols, which were treated with a catalytic amount of concentrated hydriodic acid to give 4-substituted iso-chromenes (1 H-2-benzopyrans) in reasonable yields.