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The protonation of commercially available porphyrin ligands yields a class of bifunctional catalysts able to promote the synthesis of N-alkyl oxazolidinones by CO 2 cycloaddition to corresponding aziridines. The catalytic system does not require the presence of any Lewis base or additive, and shows interesting features both in terms of cost effectiveness and eco-compatibility. The metal-free method-ology is active even with a low catalytic loading of 1 % mol, and the chemical stability of the protonated porphyrin allowed it to be recycled three times without any decrease in performance. In addition, a DFT study was performed in order to suggest how a simple protonated porphyrin can mediate CO 2 cycloaddition to aziridines to yield oxazolidinones.

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Dedicated to Professor Franco Cozzi on the occasion of his 70 th birthday. "Senatores boni viri, senatus mala bestia"The reaction between epoxides and CO 2 to yield cyclic carbonates is efficiently promoted under solvent-free and relatively mild reaction conditions (0.5 mol % catalyst loading, 0.8 MPa, 125°C) by zinc(II) complexes of pyridine containing macrocyclic ligands (PcÀ L pyridinophanes). The zinc complexes have been fully characterized, including X-ray structural determination. The [Zn(II)X(PcÀ L)]X complexes showed good solubility in several polar solvents, including cyclic carbonates. The scope of the reaction under solvent-free conditions has been studied and good to quantitative conversions with excellent selectivities have been obtained, starting from terminal epoxides. When solvent-free conditions were not possible (solid epoxides or low solubility of the catalyst in the oxirane) the use of cyclic carbonates as solvents has been successfully investigated. The remarkable stability of the catalytic system has been demonstrated by a series of consecutive runs.

The demand for azobenzenes has exponentially grown due to their wide range of applications in textile, medical, and dye industries. Here we report a procedure to synthesise azobenzenes by the dehydrogenative coupling of anilines in the presence of CoII(TPP) (TPP=dianion of tetraphenyl porphyrin) catalyst and 4‐nitrophenyl azide oxidant species. Differently substituted azobenzenes were obtained in yields up to 72 % together with 4‐nitrophenyl amine, which is the stoichiometric by‐product of the process. The procedure displayed a good sustainability due to the almost quantitative recovery of pure 4‐nitrophenyl amine that can be transformed again into the desired azide to pave the way for an efficient circular process. Experimental data supported the occurrence of a radical mechanism mediated by putative nitrene radical cobalt intermediate.