PHOTOINDUCED MOLECULAR-TRANSFORMATIONS .160. FURAN ANNELATION OF 2-HYDROXYNAPHTHOQUINONE INVOLVING PHOTOCHEMICAL ADDITION AND RADICAL FRAGMENTATION - EXCLUSION OF THE INTERMEDIACY OF [2-CYCLOADDUCT IN A ONE-POT FORMATION OF FURANOQUINONES BY THE REGIOSELECTIVE 3+2-PHOTOADDITION OF HYDROXYQUINONES WITH ALKENES(2])

2-Acetoxy-1,4-naphthoquinone underwent [2+2] photoaddition to 2-methyl propene, giving a cyclobutanol acetate exclusively. Hydrolysis of the acetate with acid gave the corresponding cyclobutanol, which was stabl e under the conditions of an alkene-quinone photoaddition; hydrolysis with a base gave a fused 1-indanone derivative. Photolysis of the hypo iodite generated from the cyclobutanol derivative with mercury(II) oxi de-iodine in benzene induced a beta-scission of the cyclobutanoxyl rad ical to give a 2,3-dihydronaphtho[2,3-b]furan-4,9-dione and its [1,2-b ]furan-4,5-dione isomer.