In a recent paper (New J. Chem., 2001, 25, 1520), we have analysed crystal structures of some N-aryl pyrimidinones. Based on the occurrence of two-dimensionallayers in six out of nine crystals, we proposed that self-assembly in these structures might be analysed in terms of the stacking of 2D hydrogen-bonded layers. We show herein that meta-substituted phenyl pyrimidinones (Br, I, F, NO2, Me, OMe)
Controlled reduction of pyrimidin(e)-2(1H)-ones and -thiones with metal hydride complexes. Regioselective preparation of dihydro- and tetrahydro-pyrimidin-2(1H)-ones and the corresponding thiones
6-Trisubstituted pyrimidin-2(1H)-ones were easily reduced with sodium borohydride to give mixtures of 3-aryl-3,4-dihydro-, 1-aryl-3,4-dihydro-, and 3,4,5,6-tetrahydro-pyrimidin-2(1H)-ones. The ratio of the three products was dramatically dependent on the reaction conditions and on the nature of the 4- and 6-substituents in the pyrimidine ring. The reaction with lithium aluminium hydride is also discussed.