4,8,8-Tribromobicyclo[5.1.0]oct-4-en-3-ones from dibromocarbene adducts of cyclohexa-1,4-dienols

Abstract

Treatment of the bisdibromocarbene adducts (I) of substituted cyclohexa-1,4-dienols with pyridine or triethylamine gave α-bromo-αβ-unsaturated ketones (II) in good yields. The dihydroxy-diadduct (I; R¹= H, R²= OH) gave the cyclo-octatrienone (IV), whereas the isomeric diadduct (I; R¹= OH, R²= H) gave 3-bromo-4-hydroxybenzocyclobuten-1(2H)-one (VIII) in poor yield.