Cyclohexanone enamine reaction with dichlorocarbene

The reaction of enamines derived from cyclohexanone with dichlorocarbene to give the 1 1 adducts is now well established (137-139). The morpholine enamine (113) reacted with dichlorocarbene at —10 to —20° in tetrahydrofuran to give the stable crystalline adduct (201). Thermal decomposition followed by an aqueous work-up gave an a,)3-unsaturated ketone identified as 2-chloromethylene-cyclohexan-l-one (202) (139). 

The reactions of dichlorocarbene with morpholine and piperidine enamines derived from cyclopentanone and cyclohexanone have been reported to lead to ring expanded and a-chloromethylene ketone products (355,356). Similarly a-chloro-a, -unsaturated aldehydes were obtained from aldehyde derived enamines (357). Synthesis of aminocyclopropanes (353,359) could be realized by the addition of diphenyldiazomethane (360) and the methylene iodide-zinc reagent to enamines (367). 

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