Evaluation of dipole moment and electrophilicity on the nature of click-type coupling reaction between thioamide and sulfonyl azide

A cooperated experimental and computational investigation on sulfonyl amidine formation from thioamides and sulfonyl azides is described. The data support a non-concerted two-step pathway for the coupling reaction and also indicate that dipole moment of thioamide and electrophilicity of sulfonyl azide would be significant factors for the reaction efficiency. A simple reactivity prediction of the coupling reaction was demonstrated by preliminary in silico evaluation for these factors, by which we successfully picked up a good pair of reactants with a high reactivity among several thioamides and sulfonyl azides in stock.