Naphtho[2,3-c]furan-4,9-dione and a Further Exploratory Approach to the Ring System of Ventilone A

Abstract

1,4-Dimethoxy-2,3-didehydronaphthalene (10), generated by the dehydrobromination of 2-bromo-1,4-dimethoxynaphthalene (9), was trapped with furan and 2-methylfuran, and the resulting adducts were converted into naphtho[2,3-c]furan-4,9-dione (1) and 1-methylnaphtho[2,3-c]furan-4,9-dione (19) respectively. An attempt to extend this procedure to the synthesis of ventilone A (2) failed when the adduct (31), derived from 6,7-methylenedioxy-1,4,5,8-tetramethoxy-2,3-didehydronaphthalene (30) and 2-methylfuran, could not be oxidizedselectively.