Studies on synthesis of N-acyl amidines and reactivity of the [3 + 2] cycloaddition according to functional groups

초록

The cyclic amidines structures have been observed in natural products and various biological inhibitors. Based on these potential biological activities of the cyclic amidines, we tried to synthesize various cyclic amidines using acyl azide and sulfonyl azide. In our previous study, borane catalyst and silane were used to create an N-silyl enamine intermediate through hydrosilylation. By adding sulfonyl azide to the reaction mixture, we could induce [3 + 2] dipolar cycloaddition reaction to form the cyclic amidines. However, acyl azide was relatively less reactive than sulfonyl azide, so the yield of cyclic amidines using acyl azide was poor. Therefore, we decided to increase the reactivity of the acyl azide by attaching electron withdrawing substituent to the acyl azide. Also we studied the reactivity of the N-silyl enamines and acyl azides with various electronic nature.