Addition of chloroketens to spiro[2.4]hepta-4,6-diene
Abstract
Addition of chloroketens to spiro[2.4]hepta-4,6-diene is regiospecific, giving 7-chlorospiro(bicyclo[3.2.0]hept-2-ene-4,1′-cyclopropan)-6-ones (6)–(10) rather than the 6-chloro-7-ketones. For alkyl-substituted chloroketens there was an increase in the proportion of 7-endo-alkyl adduct as the size of the alkyl group increased supporting a crosswise approach of the keten and spirodiene. Phenyl(chloro)keten yielded a single 6-keto-adduct with dimethylfulvene.