Rhodium-catalyzed cycloisomerization of N-propargyl enamine derivatives.

摘要: A novel rhodium-catalyzed cycloisomerization has been developed which converts N-propargyl enamine derivatives to their isomeric six-membered azacycles in good yields under mild reaction conditions. The [Rh(C2H2)2Cl]2/P(4-F−C6H4)3 catalyst, combination with DABCO as a base and DMF solvent, was found be effective promoting the cyclization process. is proposed proceed through an intramolecular nucleophilic attack of rhodium vinylidene followed by base-mediated proton-shunting play crucial role transformation, indicating proton migration integral component catalytic cycle. An aprotic polar solvent required for high conversion, points intermediacy zwitterionic intermediate. present should prove useful efficient synthesis various that are important structural motifs many natural isolates medicinal agents.