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Ethyl 6-methyl-4-phenyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate
Abstract
The title compound, C14H16N2O2S, was prepared by the reaction of benzaldehyde, ethyl acetoacetate and thiourea sulfate. There are weak intermolecular hydrogen-bond interactions in the crystal structure, involving the amine and thioketone groups as donors and acceptors, respectively.
In the title compound, C13H13FN2O2S, the pyrimidine ring adopts a twist-boat conformation with the MeCN and methine-C atoms displaced by 0.0938 (6) and 0.2739 (3) Å, respectively, from the mean plane through the other four atoms of the ring. The 2-fluorobenzene ring is positioned axially and forms a dihedral angle of 89.13 (4)° with the mean plane through the pyrimidine ring. The crystal structure features N—H⋯O, N—H⋯S and C—H⋯O hydrogen bonds that link molecules into supramolecular chains along the b axis. These chains are linked into a layer parallel to (10-1) by C—H⋯π interactions; layers stack with no specific interactions between them.
In the title compound, C13H13FN2O2S, the pyrimidine ring adopts a twist-boat conformation with the MeCN and methine-C atoms displaced by 0.0938 (6) and 0.2739 (3) Å, respectively, from the mean plane through the other four atoms of the ring. The 2-fluorobenzene ring is positioned axially and forms a dihedral angle of 89.13 (4)° with the mean plane through the pyrimidine ring. The crystal structure features N—H⋯O, N—H⋯S and C—H⋯O hydrogen bonds that link molecules into supramolecular chains along the b axis. These chains are linked into a layer parallel to (10-1) by C—H⋯π interactions; layers stack with no specific interactions between them.
The molecular structures of (E)-1-(4-{[1-(4-fluorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl]diazenyl}phenyl)ethanone, C19H17FN4O, (III), and (E)-1-(4-chlorophenyl)-3,5-dimethyl-4-[2-(2-nitrophenyl)diazenyl]-1H-pyrazole, C17H14ClN5O2, (IV), prepared by reaction of the corresponding β-diketohydrazones with substituted arylhydrazines in acid media, are nonplanar, with the planes of the lateral phenyl rings forming dihedral angles with that of the central pyrazole ring varying from 2.71 (7) to 45.22 (7)°. The crystal structures are supported by C—H...O, C—H...π and π–π weak intermolecular interactions together with some unusual trifurcated C—Cl...Cl—C contacts, which are discussed in detail.
Two sulfanylidene-1,2,3,4-tetrahydropyrimidine derivatives have been synthesized using acid-catalysed cyclocondensation reactions between thiourea, ethyl 3-oxobutanoate and substituted benzaldehydes. In each of ethyl (4RS)-4-(4-benzyloxyphenyl)-6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxylate, C21H22N2O3S, (I), where Z′ = 2, and ethyl (4RS)-4-(4-methoxyphenyl)-6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxylate 0.105-hydrate, C15H18N2O3S·0.105H2O, (II), the reduced pyrimidine ring adopts a conformation intermediate between the boat, screw-boat and twist-boat forms. In (I) and (II), a combination of N—H...O and N—H...S hydrogen bonds links the organic molecules into ribbons containing alternating R22(8) and R44(20) rings. In (I), the ribbon contains three types of ring, viz. two different R22(8) rings which are both centrosymmetric and R44(20) rings which are not centrosymmetric. In (II), the ribbon contains two types of ring, both of which are centrosymmetric. In compound (II), the ribbons enclose continuous channels which run along the twofold rotation axes in the space group C2/c, and the partial-occupancy water molecules lie within these channels. Structural comparisons are made with a number of related compounds.
The title compound, C14H11N5S, was prepared by the reaction of 4-amino-5-(3-pyridyl)-1H-1,2,4-triazole-5(4H)-thione and benzaldehyde with ethanol at room temperature. The dihedral angles formed by the benzene and pyridine rings with the triazole ring are 46.2 (1) and 35.1 (2)°. There are weak inter- and intramolecular hydrogen bonds in the crystal structure.
The supramolecular structures of eight aryl protected ethyl-6-methyl-4-phenyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylates were analyzed in order to understand the effect of variations in functional groups on molecular geometry, conformation and packing of molecules in the crystalline lattice. It is observed that the existence of a short intra-molecular C–H/p interaction between the aromatic hydrogen of the aryl ring with the isolated double bond of the six-membered tetrahydropyrimidine ring is a key feature which imparts additional stability to the molecular conformation in the solid state. The compounds pack via the cooperative involvement of both N–H/ S]C and N–H/O]C intermolecular dimers forming a sheet like structure. In addition, weak C–H/O and C–H/p intermolecular interactions provide additional stability to the crystal packing.
The title compound, C(9)H(10)N(4)O(2)S, was prepared by the reaction of 1-(4-nitro-phen-yl)ethanone and thio-semicarbazide in ethanol at 367 K. There are weak inter-molecular N-H⋯S and N-H⋯O hydrogen-bonding inter-actions in the crystal structure involving the amine and nitrile groups, respectively, as donors.
The title compound, C9H14N2O2S, belongs to a group of esters of 2-oxo- and 2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acids, which exhibit a wide spectrum of biological activities. The conformation of the pyrimidine ring is a distorted boat. In the crystal structure, hydrogen-bonded centrosymmetric dimers are formed via intermolecular N -H⋯S hydrogen bonds. The dimers are linked by intermolecular N - H⋯O hydrogen bonds to form a two-dimensional network. © 2005 International Union of Crystallography Printed in Great Britain - all rights reserved.
The structures of two unsymmetrically substituted thiourea derivatives, C11H14N2OS, (1), and C12H16N2OS, (2), are reported. In (1), the two molecules present in the asymmetric unit show differences in the orientations of the phenyl and cyclohexyl rings. In both of the structures, N-H ... S hydrogen bonds link the molecules into chains that run parallel to a crystallographic axis.
The puckering characteristics of C17H20CIN3 O3S2, the hexahydropyrimidine ring was described. It was found that the four C-N bond distances in the hexahydropurimidine ring shows wide variation and distances were found to be longer than the mean value of 1.333 Å for pyrimidines. It was observed that the largest deviation from the best plane were -0.256 (2) Å for C5 and 0.266 (2) Å for C6. It was also found that the pyrimidine derivatives show potential bacteriostatic, fungicidal and antiviral activities.