A new heterocyclic reductive alkylating agent, 2-chloromethyl-3-nitroimidazo [1, 2-a] pyrimidine, is synthesized for the first time and shown to react under phase-tranfer catalysis conditions with 2-nitropropane anion to give good yield of the C-alkylated derivative. Elimination of nitrous acid allows to obtain a new class of imidazo [1, 2-a] pyrimidine derivatives bearing a trisubstituted ethylenic bond in the 2 position. The SRN1 mechanism ...