C2v-symmetric metalloporphyrin promoted cycloaddition of epoxides with CO2 under atmospheric pressure

A series of C 2 v -symmetric diphenylporphyrin complexes containing a metal ion (Mg, Al, Mn, Fe, Co, Zn) have been synthesized and applied as catalysts for the solvent-free cycloaddition of epoxides and carbon dioxide under atmospheric pressure and mild temperature, in concert with phenyltrimethylammonium tribromide (PTAT) as a co-catalyst. The activity of these catalysts deeply relies on their coordinated metal species. [5,15-Diphenylporphyrin]manganese(III) chloride ( DPP-MnCl ) has been found to be the most effective catalyst under optimal reaction conditions. It's worth mentioning that the cycloaddition of phenyl glycidyl ether (GPE) and CO 2 proceeded successfully by DPP-MnCl /PTAT even at 25 °C and atmospheric pressure. Moreover, preliminary kinetic investigations of this cycloaddition were carried out by using catalysts DPP-MnCl , DPP-CoCl and DPP-Zn , revealing that the (phenoxymethyl)ethylene carbonate (PEC) formation with the lowest activation energy is catalyzed by DPP-MnCl . Furthermore, a Lewis acid-base dual cooperative catalytic mechanism has been carefully proposed in light of the catalyst systems and the experimental results.