ChemInform Abstract: Thermal Reactions of a 2-Aryl-1-vinylcyclobutanol

Thermolysis reactions of the exo (distal) and endo (proximal) isomers of 7-vinyl-6b,8,8a-tetrahydrocyclobut[a]acenaphthylen-7-ol (1a and 1b) have been studied, both in refluxing xylene and in a packed pyrolysis column. These epimers were prepared from the corresponding cyclobutanone (3). An oxy-Cope rearrangement of 1b was not observed under any conditions. Both epimers gave the same thermolysis products, a fused cyclohexanone derivative 15 (a formal [1,3] shift product) and vinyl ketone 16 (a retro-ene product). At temperatures above 250 °C some acenaphthylene was also obtained. The anionic oxy-Cope variant gave only 15. A common diradical intermediate is proposed for the thermal reactions.