A convenient preparation of functionalized 1,8-dioxygenated naphthalenes from 6-alkoxybenzocyclobutenones

Abstract

An alternate route for the synthesis of naphthalene building blocks 1-4 has been developed, starting from readily available 6-alkoxybenzocyclobutenones. As thermolysis of a propynylbenzocyclobutenol only provided the naphthalene in low yield, allenyl-substituted benzocyclobutenols were investigated. The desired allenic precursors were prepared by a two-step procedure, which involved hydroxyl-directed reduction of the chloropropargylbenzocyclobutenols obtained from addition of lithiopropargyl chloride to the benzocyclobutenones. Thermolysis of the allenic alcohols gave the desired naphthalenes in good yields.