Enamine chemistry – XV^†. The reaction of enamines with α-halogeno electrophilic olefins

Reaction of cyclohexanone enamines with α-chloroacrylonitrile and methyl α-chloroacrylate in polar solvents leads to hexahydroindolium salts of type 3. In ether solution at low temperature cyclobutanes, 9, are produced.