Facile synthesis of 3-(pyrazol-1-yl) succinimides from Ag2CO3 -catalyzed aza-Michael addition of pyrazoles to maleimides

Herein, an effective and facile synthesis of 3-(pyrazol-1-yl) succinimides is first presented through silver-catalyzed aza-Michael addition of pyrazoles to maleimides. In the presence of 5 mol% of Ag2CO3, various pyrazoles smoothly reacted with maleimides in dichloroethane at 100 degree celsius, to generate 3-(pyrazol-1-yl) succinimides in excellent yields. Notably, 3-substituted asymmetric pyrazoles exclusively give 3-pyrazolyl succinimides in excellent yields possibly due to the steric bulk of the 3-substituent excluding the formation of addition products of N-2. The method can also extend to gram scale.