One-pot synthesis of small spirocarbocycles through the catalytic cyclometalation reactions of unsaturated compounds

摘要: The mild and efficient one-pot methods to synthesize substituted spirocyclopropanes and spirocyclobutanes are reported. The elaborated procedures based on consecutive cycloalumination of methylenecyclopropanes, methylenecyclobutanes or cycloalkynes assisted by alkyl aluminums and Cp2ZrCl2 as a catalyst provide the formation of target products through Pd catalyzed carbocyclization of the aluminacyclopentane and aluminacyclopentene intermediates with Me2SO4 or allyl chloride.