SYNTHESIS OF 1,2-DIHYDRO-3-BENZOXEPINS BY THE REACTION OF 2-LITHIO-β-METHOXYSTYRENES WITH EPOXIDES FOLLOWED BY HYDRIODIC ACID CATALYZED CYCLIZATION

5-Substituted 1,2-dihydro-3-benzoxepins can be prepared in reasonable overall yields from a-substituted 2-bromo-beta-methoxystyrenes. Thus, the reaction of alpha-substituted 2-lithio-beta-methoxystyrenes, generated by the bromine-lithium exchange between alpha-substituted 2-bromo-beta-methoxystyrenes and butyllithium, with epoxides gives the corresponding 2(methoxyvinyl)phenethyl alcohols. These undergo cyclization with a loss of methanol on treatment with a catalytic amount of hydriodic acid to give the desired products.