simple and efficient method for the synthesis of 3‐oxopropanenitriles from variously substituted heterocyclic compounds via direct electrophilic cyanoacetylation is described. A series of heterocyclic 3‐oxopropanenitriles (2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2i, 2j, 2k) have been synthesized using mixed anhydride (acetic or trifluoroaceticanhydride:cyanoacetic acid) in the presence of Mg(ClO4)2·2H2O as