The CO2 cycloaddition to epoxides and aziridines promoted by porphyrin-based catalysts

Thanks to its intrinsic eco-compatibility and high atom economy, the direct insertion of CO2 into three-membered rings, such as epoxides and aziridines, has become one of the most investigated strategies for the synthesis of cyclic carbonates and oxazolidin-2-ones. In this view, the following short account summarizes our recent results regarding the use of ruthenium porphyrin complexes and metal-free porphyrins, in combination with TBACl (tetrabutyl ammonium chloride), to promote the CO2 conversion into cyclic carbonates as well as N-alkyl and N-aryl oxazolidin-2-ones. Experimental data are described in combination with performed DFT studies that allowed proposing a reaction mechanism for the CO2 cycloaddition to aziridines promoted by metal-free porphyrins in which the adduct formed by TPPH2 and TBACl represents the real catalytic active species.