Microwave assisted solid phase catalyst-free Biginelli synthesis of 3,4-dihydropyrimidin-2(1<i>H</i>)-one and 3,4-dihydropyrimidin-2(1<i>H</i>)-thione: A green approach, characterization and molecular crystal structures

Solid phase catalyst-free Biginelli synthesis of novel 5-carbethoxy-4-(3-bromo-4-hydroxy-5-methoxyphenyl)-6-methyl-3,4-dihydropyrimidin-2(1H)-one (C15H17BrN2O5) and 5-carbethoxy-4-(3-bromo-4-hydroxy-5-methoxyphenyl)-6-methyl-3,4-dihydropyrimidin-2(1H)-thione (C15H17BrN2O4S) has been carried out under microwave irradiation at 400W. The structures of both compounds were confirmed by 1H NMR, 13C NMR, Mass, FT-IR, Elemental analysis, and single crystal X-ray diffraction method. The single crystals of both compounds were obtained by crystallization in 0.35 × 0.30 × 0.25 mm dimension for (C15H17BrN2O5) and 0.35 × 0.32 × 0.30 mm dimension for (C15H17BrN2O4S). Both compounds, (C15H17BrN2O5) and (C15H17BrN2O4S) crystallizes in the monoclinic P21/c space group and shows four and two intermolecular hydrogen bonds, respectively.