Azepinones. Part 4. Electrocyclic and cycloaddition reactions of simple 1H-azepin-3(2H)-ones

Abstract

Photolysis of the azepinone (2) gives the bicyclic photoproduct (5) in 64% yield; this compound reverts cleanly to the starting material (2) on thermolysis in toluene. Cycloaddition reactions of the azepinones (1) or (2) with maleic anhydride generate the endo adducts (7) or (8), respectively, whereas treatment of (1) with acetylenic dienophiles gives rise to benzenoid compounds after cleavage of the three-atom bridge.