A useful α, α′ - annulation reaction of enamines

The reactions of a series of enamines generated from a range of cyclic ketones with chloromethyl and iodomethyl vinyl ketone have been studied. The principal products are bridged ring diketones. The four carbon bridge, bearing a 2-oxobutyl function, spans the α and α′ carbons of the original cyclanone. Presumptive evidence as to the pathway of this novel one step bridging annulation is provided.