Intramolecular cyclization of cycloalkene carboxylic acid chlorides

Thermal cyclization of cyclooctene-4-yl-carboxylic acid chloride (5) and cycloheptene-4-yl-carboxylic acid chloride (10) yielded mixtures of mainly endo and exo 2-chlorobicyclo3.3.1]nonane-9-one (7 and 8), and mixtures of endo and exo 2-chlorobicyclo3.2.1]octane-8-one (12 and 13), respectively. AlCl₃-catalyzed cyclization of 10 gave the same product composition as the uncatalyzed reaction. In the AlCl₃-catalyzed cyclization of 5 considerable amounts of bicyclo3.3.1]non-2-en-9-one (6) and exo 3-chlorobicyclo3.3.1]nonane-9-one (9) were obtained in addition to 7 and 8.