With metal or not? a computationally predicted rule for a dirhodium catalyst in [3+3] cycloadditions of triazole with thiirane

A mixture of pathways including the use of catalyst was proposed for a dirhodium-mediated triazole activation-cycloaddition. This proposal was supported by the results of density functional theory (DFT) calculations, and was indicated to involve a non-catalyzed cleavage of the triazole N-N bond followed by a dirhodium-assisted denitrogenation. Electron-deficient carboxylates were found to be favourable for the rate-determining denitrogenation step. Three possible pathways were explored to determine the inherent role of dirhodium in triazole transformation/functionalization.