“…The reaction proceeds via the ketone (346). 357 Treatment of (346) with trifluoroacetic acid gives carvenone together with the ester (347), and toluene-psulphonic acid in refluxing benzene converts (346) into carvenone and the isomeric ketone (348).357 Photolysis of the acetyl derivative (349) gives a mixture of (350) and (351). If the irradiation is through a Corex filter, and (349) is in solution in acetone, the products are the cyclopentenes (352) and (353).358 Photolysis of the methoxy-ketone (354), in ethanol solution, gives the cleavage product (359, while its epimer (356) yields ( 357) and (358), which are the known irradiation products of cis-caran-4-one (359).…”