The reaction of cycloheptatriene with dichloroketene, generated by the treatment of trichloroacetyl chloride with activated zinc in dry diethyl ether, affords 9, 9-dichlorobicyclo [5.2. 0] nona-2, 4-dien-8-one 2 as a major product together with 3′, 3′, 9, 9- tetrachlorospiro (bicyclo [5.2. 0] nona-2, 4-diene-8, 2′-oxetan)-4′-one 3. Structure 3 is elucidated by the X-ray crystallographic analysis of its partially reduced product. Lactone 3 ...
