Theoretical Study On The Mechanisms Of Cu-catalyzed Cycloadditions And Fe-catalyzed Carbonylations

The Cu(â… )-catalyzed [4+1] cycloadditions between acetylenic ketones and diazoacetates, and the Fe-catalyzed synthesis of succinimides are separately studied using the density functional theory (DFT) with the B3LYP functional in this paper. Based on the computed results, we get the possible reaction paths. All the geoemtries of intermediates and transition states are optimized completely. The rationality of the geometries of some key transition states are affirmed using the IRC scanning. The reaction mechanism is predicted based on the calculated dominant path. In addition, the PCM model is used to consider the solvent effect.1 Theoretical study the mechanism of Cu(â… )-catalyzed [4+1] cycloadditions between acetylenic ketones and diazoacetatesThe reaction mechanism of the Cu(â… )-catalyzed [4+1] cycloadditions betweenα,β-acetylenic ketones and diazoacetates is studied using the density functional theory (DFT) with the B3LYP functional. In this system the diazo compounds release the N₂ and lead to the metal carbine, then the subsequent reactions are triggered by the metal carbene, and the furan derivatives are producted by the [4+1] cycloadditions. The results indicate that there are two possible reaction paths, and the reaction between metal carbine and carbonyl group is the favorable reaction path. In addition, the PCM model is used to consider the solvent effect (the ClCH₂CH₂Cl is used as solvent). Moreover, the solvent reduces the relative energies of the transition states and intermediates and all the solvent effects are negative.2 Theoretical study on the mechanism of Fe-catalyzed synthesis of succinimidesThe reaction mechanism of the synthesis of succinimides using hexyne and ammonia catalyzed by Fe compounds (Fe(CO)₅ and Fe₃(CO)₁₂) is studied using the density functional theory (DFT) with the B3LYP functional. The reaction mechanism is predicted based on the calculated data. The calculated results indicate that the two catalysts, (Fe(CO)₅ and Fe₃(CO)₁₂, have the similar catalytic mechanisms in the synthesis of succinimides. Firstly the ammonia substitutes the carbon monoxide and at the same time the hexyne coordinates with the transition metal atom of the catalysts. After a two-step carbonylation, the hydrogen of ammonia migrates to the ketonic oxygen atom. According to our calculations, it is found that the hydrogen transfer is the rate-controlling step. Finally, the nitrogen atom attacks the carbon atom to lead the formation of the C-N bond. It is suggested that the energy is lower when the reaction is catalyzed by the Fe₃(CO)₁₂. In addition, the reaction takes place easily in the solvent of THF.