Synthesis of polysubstituted 3H-pyrimidin-4-ones from cyanoacetamides under Vilsmeier conditions

A facile and efficient approach to a variety of 6-chloro-3,5-disubstituted 3H-pyrimidin-4-ones 2/6 from the readily available cyanoacetamides 1/5 under Vilsmeier conditions was developed, in which the Vilsmeier reagent plays multiple roles and the possible mechanism is discussed.