Rhodium-catalyzed Cyclization Of Ene-diynes

Since the discovery of the Wilkinson catalyst in the mid of 1960's, organorhodium chemistry has been received much attention of the chemists. In recent years, our group have done much work and gotten many pretty results in terms of electron-deficient conjugated enyne. In this dissertation, I have focused on the design and development of the rhodium-catalyzed cyclization of enynes. The whole dissertation contains three parts:Partâ… :One-Pot Synthesis of Fused Tricyclic Heterocycles by Sequential Rhodium-catalyzed Pauson-Khand Reaction and Formal [3+3] Cycloaddition We have developed a protocol for the construction of bicyclic electron-deficient conjugated enyne from the readily available 1-ene-6,8-diynes or 1-ene-7,9-diynes via Rh-catalyzed Pauson-Khand reaction. Moreover, one-pot synthesis of fused tricyclic heterocycles with a quaternary carbon center by sequential rhodium-catalyzed Pauson Khand reaction and formal [3+3] cycloaddition has been established.Partâ…¡:Rhodium-Catalyzed Nucleophilic Tandem Cyclization of Diyne-enones with Alcohols We have established the tandem nucleophilic addition and cyclization of diyne-enones with alcohols catalyzed by rhodium complex to afford the bicyclic furan compounds in good yields. The alcohols acting as nucleophiles could be primary and secondary alcohol. Furthermore, the corresponding product with a convertible hydroxy group could also be obtained when the water was used as the nucleophile. The reaction of various diyne-enone proceeded smoothly to give the corresponding product in moderate to excellent yields.Partâ…¢:Rhodium-Catalyzed [3+2+2] Cycloaddition of Diyne-enone with Alkynes We have also studied the Rh-catalyzed tandem cyclization [3+2+2] cycloaddition of diyne-enones with alkynes including terminal and internal alkyne, in which four new bonds were formed and a fused tricyclic compound was constructed. The regioselectivity shows a significant dependence on the nature of the substituents of the alkyne.