Expeditious synthesis of 5,6,7,8-tetrahydro-imidazo[1,2-a]pyrimidin-2-ones and 3,4,6,7,8,9-hexahydro-pyrimido[1,2-a]pyrimidin-2-ones

A convenient synthesis of new 5,6,7,8-tetrahydro-imidazo[1,2-a]pyrimidin-2-ones and 3,4,6,7,8,9-hexahydro-pyrimido[1,2-a]pyrimidin-2-ones from the Baylis–Hillman adducts of acrylonitrile and their derivatives is described. A common strategy employed to achieve the syntheses of title compounds involved generation of diamines from different Baylis–Hillman derivatives followed by treatment with cyanogen bromide at reflux temperature to trigger a double intramolecular cyclization.