Gong-Chun Li

Highly Regioselective Synthesis of Novel 4-O-Phosphorylated Paeonol Analogs

Abstract 4-O-phosphorylated paeonol derivatives were conveniently prepared by a facile method. Resacetophenone was prepared by the Friedel–Crafts acylation reaction of acetic acid with resorcinol. It was then phosphorylated regioselectively at the 4-O position using the Atherton–Todd reaction. An efficient, highly regioselective method to synthesize 4-O-phosphorylated paeonol derivatives is provided, and the approach has the merits of mild reaction conditions. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT

Ethyl 6-[4-(dimethyl­amino)phen­yl]-4-hydr­oxy-2-oxo-4-(trifluoro­methyl)­hexa­hydro­pyrimidine-5-carboxyl­ate

The title compound, C16H20F3N3O4, was prepared by reaction of 4-(dimethylamino)benzaldehyde, ethyl 4,4,4-trifluoro-3-oxobutanoate and urea. In the title molecule, the pyrimidine ring adopts a half-chair conformation and there is an intramolecular hydrogen bond (O—H⋯O). The crystal structure is stabilized by two types intermolecular hydrogen bonds (N—H⋯O and N—H⋯N).

Ethyl 6-(4-fluoro-phen-yl)-4-hy-droxy-2-oxo-4-trifluoro-meth-yl-1,3-diazinane-5-carboxyl-ate monohydrate.

The asymmetric unit of the title compound, C14H14F4N2O4·H2O, contains two crystallographically independent organic molecules and two water molecules. The two 1,3-diazinane rings adopt a half-chair conformation and the dihedral angles between their mean planes and those of the benzene rings are 75.65 (4)° and 49.41 (3)° in the two molecules. The crystal structure is stabilized by intermolecular O—H⋯O and N—H⋯O hydrogen bonds.

Highly Chemoselective Synthesis of Novel 6-O-phosphorylated 6-Hydroxypyridazine-3(2H)-one

GRAPHICAL ABSTRACT Abstract 6-O-Phosphorylated pyridazine-3(2H)-one derivatives were conveniently prepared by a facile method. Maleic hydrazide was prepared by the condensation of maleic anhydride with 85% hydrazine hydrate. It was then chemoselectively phosphorylated at the 6-O position using the Atherton–Todd reaction. An efficient, highly chemoselective method to synthesize 6-O-phosphorylated pyridazin-3(2H)-one derivatives is provided, and the approach has the merits of mild reaction conditions.

1-(4-tert-Butyl­benz­yl)pyrimidine-2,4(1H,3H)-dione

The asymmetric unit of the title compound, C15H18N2O2, contains two independent molecules with essentially identical geometries and conformations. The dihedral angles between the benzene and pyrimidine rings in the two molecules are 89.96 (11) and 73.91 (11)°. The six methyl groups are disordered over two sets of sites, with site occupancies of 0.545 (4):0.455 (4) and 0.542 (7):0.458 (7) in the two molecules. The crystal structure is stabilized by N—H⋯O hydrogen bonds.

6-Benz-yloxy-2-phenyl-pyridazin-3(2H)-one.

In the title compound, C17H14N2O2, the central pyridazine ring forms dihedral angles of 47.29 (5) and 88.54 (5)° with the benzene rings, while the dihedral angle between the benzene rings is 62.68 (6)°. In the crystal, molecules are linked by two weak C—H⋯O hydrogen bonds and three weak C—H⋯π interactions.

1,3-Bis(4-tert-butyl-benz-yl)pyrimidine-2,4(1H,3H)-dione.

In the crystal structure of the title molecule, C26H32N2O2, the six methyl groups are disordered over two positions, with site-occupancy ratios of 0.665 (8):0.335 (8) and 0.639 (8):0.361 (8). The central pyrimidine ring is almost planar with an r.m.s. deviation of 0.009 Å. The dihedral angles formed by the two benzene rings with the pyrimidine ring are 70.70 (8) and 88.02 (9)°. The dihedral angle between two benzene rings is 46.67 (10)°.

6-(Trifluoro-meth-yl)pyrimidine-2,4(1H,3H)-dione monohydrate.

The title compound, C5H3F3N2O2·H2O, was prepared by the reaction of ethyl 4,4,4-trifluoro-3-oxobutanoate with urea. In the crystal, the 6-(trifluoromethyl)pyrimidine-2,4(1H,3H)-dione and water molecules are linked by N—H⋯O and O—H⋯O hydrogen bonds. A ring dimer structure is formed by additional intermolecular N—H⋯O hydrogen bonds.

1-Benzoyl-4-(2-nitro-phen-yl)semicarbazide.

The title compound, C14H12N4O4, was prepared by the reaction of 2-nitrophenyl isocyanate with benzoylhydrazine. The dihedral angle between the rings is 71.49 (6)) Å. The molecular conformation is stabilized by an intramolecular N—H⋯O hydrogen bond, generating an S(6) ring. The crystal packing shows N—H⋯O hydrogen bonds.

1,3-Bis(4-meth­oxy­benz­yl)-6-methyl­pyrimidine-2,4(1H,3H)-dione

The title compound, C(21)H(22)N(2)O(4), was prepared by reaction of 6-methyl-pyrimidine-2,4(1H,3H)-dione and 1-chloro-methyl-4-meth-oxy-benzene. In the title mol-ecule, the central pyrimidine ring forms dihedral angles of 62.16 (4) and 69.77 (3)° with the two benzene rings. In the crystal, weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into chains.