Abstract 1-Alkenylbenzocyclobuten-1-ols, prepared from benzocyclobutenones via the addition of alkenylmagnesium bromides, or the addition of alkynyllithium reagents followed by (E)-selective reduction of the triple bond, undergo successive thermal 4π and 6π electrocyclic reactions leading to substituted 3, 4-dihydro-1 (2H)-naphthalenones.