Diastereoselective Intermolecular Rhodium-Catalyzed[4+2+2]Carbocyclization Reactions:Computational and Experimental Evidence for the Intermediacy of an Alternative Metallacycle Intermediate

摘要

Intermolecular rhodium-catalyzed[m+n+o]reactions of 1,6-enynes and various pi-components(carbon monoxide,alkynes,1,3-butadienes,etc.)provide an expeditious approach for the construction of polycyclic fragments that represent important synthons for target-directed synthesis.We recently reported a diastereoselective intermolecular rhodium-catalyzed[4+2+2]Carbocyclization reaction of the substituted 1,6-enyne 1(R_1/R_2 = Me,R_3 = H)with 1,3-butadiene to afford the corresponding bicyclic octanoid 2 in high yield(eq 1).