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In the search for better herbicides a series of 1-alkyl-3-(α-hydroxy-(un)substituted benzylidene)pyrrolidine-2,4-diones were prepared and their structure-activity relationships studied. All their structures have been confirmed by 1H-NMR andelemental analysis. The preliminary bioassay results indicated that some of them have highherbicidal activity against annual dicotyledonous and monocotyledonous plants.

In the title molecule, C19H15F3N2O, the benzene rings of the tolyl and trifluoromethylphenyl groups form dihedral angles of 64.1 (2) and 38.5 (2)°, respectively, with the pyridazine ring. The CF3 group is disordered over two orientations, with site-occupancy factors of ca 0.56 and 0.44.

The title compound, C15H13F3N2O, contains one benzene ring, one cyclohexane ring and a pyridazine ring. The dihedral angle formed by the pyridazine ring with the benzene ring is 61.5 (2)°. The crystal structure is stabilized by two intermolecular hydrogen bonds (N—H...O and C—H...F). The cyclohexane ring adopts a screw-boat conformation. The CF3 group is disordered over two positions; the site occupancy factors are ca 0.6 and 0.4.

The title compound, C24H27N3O4, also known as fenpyroximate, is a commercial acaricide. The benzene ring of the phenoxy group is approximately perpendicular to the pyrazole ring with a dihedral angle of 84.37 (11)°. The dihedral angle between the phenoxy and the benzoate benzene rings is 48.83 (8)°.

Abstract  An efficient, fast and facile pyrazolo[1,5-a]pyrimidine synthetic protocol has been established by the condensation of aminopyrazoles with 1,3-dicarbonyl components in AcOH/H2SO4 system. The pyrazolo[1,5-a]pyrimidine sulfides were selectively oxidized to the sulfones via a temperature-controlled stepwise oxidative fashion. The correlation between the substitution patterns of these pyrazolo[1,5-a]pyrimidines and their fluorescent spectroscopic properties were further examined, which provided the fundamentals for their potential applications in the development of new fluorescent probes. Red-shifts were easily achieved by the incorporation of unsaturated groups at the 5- and 7-positions, which suggested an approach for synthesizing long wavelength pyrazolo[1,5-a]pyrimidine dyes. The fluorescent spectroscopic properties were found to be sensitive to the hydroxy-containing and carbonyl-containing media such as alcohol and acetone, which helps to confirm the promising perspectives of further investigations in this area. [ABSTRACT FROM AUTHOR]

A series of novel α,α,α-trifluoro-m-tolyl pyridazinone derivatives was synthesised. Herbicidal activities of the two intermediate compounds and 15 pyridazinone derivatives were evaluated through barnyardgrass and rape cup tests and Spirodela polyrrhiza (L.) Schleiden tests. Selected compounds were also evaluated under greenhouse conditions. Bleaching activities were observed at 10 µg ml-1 and some compounds exhibited herbicidal activities at a rate of 300 g ha-1. The relationship between crystal structures and herbicidal activities is discussed through a comparison of two compounds (5a and 5f). [ABSTRACT FROM AUTHOR]

The structures of methyl 5-[2-chloro-4-(trifluoromethyl)Phenoxy]-2-nitrobenzoate, C15H9ClF3N3O5, (I), methyl 2-chloro-5-[3-methyl-2,6-dioxo-4-(trifluoromethyl)-1,2,3,6-tetrahydro-pyrimidin-1-y1]benzoate, C14H10ClF3N2O4, (II), and 2-[4-chloro-2-fluoro-5(prop-2-ynyloxy)phenyl]-4-(trifluoromethyl)piperidine-2.6-dione, C15H10ClF4NO3, (III), are similar in their dihedral angles and in the distances between the farthest two atoms. There are two independent molecules in the structure of (I). The dihedral angles between the two aromatic rings in each molecule in (I), between the benzene and tetrahydropyrimidine rings in (II), and between the benzene ring and the five-atom planar portion of the piperidine-2,6-dione ring in (III) are 80.78 (11)189.75 (11), 89.13 (9) and 87.52 (13)°, respectively. The distances between the farthest two atoms, viz. O···F in the two molecules of (I), and Cl···F in (II) and (III), are 11.763 (7)111.953 (6), 10.734 (10) and 10.889 (9) Å, respectively. In all three crystal structures, the molecules are linked to generate sheets of molecules via C—H···O interactions. [ABSTRACT FROM AUTHOR]

The molecular structures of 2-[4-chloro-2-fluoro-5-(prop- 2-ynyloxy)phenyl]-1,3,4,5,6,7-hexahydroisoindole-1,3-dione, C17H13ClFNO3, (I). and the isomeric compound 2-[4-chloro-2-fluoro-5-(prop-2-ynyloxy)phenyl]-cis-1,3,3a,4,7,-7a-hexahydroisoindole-1,3-dione, (II), are, as anticipated, significantly different in their conformations and in the distances between the farthest two atoms. The six-membered ring of the 1,3,4,5,6,7-hexahydroisoindole-1,3-dione moiety in (I) adopts a half-chair conformation. The dihedral angle between the five-membered dione ring of (I) and the benzene ring is 50.96 (7)°. The six-membered ring of the cis-1,3,3a,4,7 ,7a-hexahydroisoindole-1,3-dione moiety in (II) adopts a boat conformation. The dihedral angle in (II) between the five-membered dione ring and the benzene ring is 61.03 (13)°. In the crystal structures, the molecules are linked by C—H··· hydrogen bonds and weak π-π interactions. Compound (I) is a much more potent herbicide than (II). The Cl···H distances between the farthest two atoms in (I) and (II) are 11.37 and 9.97 Å, respectively. [ABSTRACT FROM AUTHOR]

The molecular structures of ethyl 5-amino-3-(4,6-dimethylpyrimidin-2-ylamino)-1-methyl-1H-pyrazole-4-carboxylate, C13H18N6O2, (I), and ethyl 5-amino-3-(4,6-dimethylpyrimidin-2-ylamino)-1-(2-nitrophenylsulfonyl)-1H-pyrazole-4-carboxylate, C18H19N7O6S, (II), have been determined. There are two intramolecular N—H…O bonds and one intermolecular N—H…O hydrogen bond in (I). The rings formed by the N—H…O hydrogen bonds are almost planar. In (II), three intramolecular N—H…O hydrogen bonds exist. [ABSTRACT FROM AUTHOR]

In the crystal structure of the title compound, C20H20N2O4, the mol­ecules are linked by a weak inter­molecular C—H⋯N hydrogen bond. The molecule has crystallographic twofold rotation symmetry. [ABSTRACT FROM AUTHOR]

The title compound, C16H15F3N2O3, is composed of a 3-(tri­fluoro­methyl)­phenyl ring and a pyridazinone ring, which are approximately coplanar, and an ethyl acetate group on the pyridazinone ring. In the crystal structure, centrosymmetric­ally related mol­ecules form dimers through non-classical intermolecular C—H⋯O hydrogen bonds. [ABSTRACT FROM AUTHOR]

The tetra­hydro­pyrimidine ring of the title mol­ecule, C12H14N2OS, adopts a half-chair conformation. In the crystal structure, the mol­ecules are linked to form centrosymmetric­ally related hydrogen-bonded dimers. [ABSTRACT FROM AUTHOR]

The article presents information related to the organic compound 3-(2-Chlorobenzyl)-2-thioxoperhydro-pyrimidin-4-one. The tetrahydropyrimidine ring of the compound adopts a half-chair conformation. The derivatives of uracil and thiouracil are known for their varied bioactivity. Lenacil, bromacil, butafenacil, flupropacil, isocil and terbacil are widely used as herbicides. Some of them possess antidiabetic activity. This led researchers to pay more attention to the synthesis and structure determination of these compounds.

In the title molecule, C18H18ClN5O2, the central pyrazole ring is perpendicular to the benzene ring and approximately perpendicular to the pyridazine ring [dihedral angles 89.9 (2) and 82.8 (2)°, respectively]. [ABSTRACT FROM AUTHOR]

The pyrazolo[1,5- a]pyrimidine ring system of the title compound, C15H12N4S, is essentially planar and the dihedral angle between the plane of the pyrazolo[1,5- a]pyrimidine system and the plane of the phen­yl ring is 134.6 (7)°. [ABSTRACT FROM AUTHOR]

The title mol­ecule, C11H9FN2O, was synthesized from 3,6-difluoro­pyridazine, benz­yl alcohol and sodium hydro­xide in CH3CN under reflux. The asymmetric unit contains two independent mol­ecules with nearly identical geometry. In the crystal structure, the mol­ecules are linked by weak inter­molecular C—H⋯F hydrogen bonds and C—H⋯π inter­actions. [ABSTRACT FROM AUTHOR]

In the title compound, C14H15ClN2O, the benzene and pyrimidine rings are nearly perpendicular, the dihedral angle between them being 84.7 (2)°. [ABSTRACT FROM AUTHOR]

In the crystal structure of the title compound, C9H9ClN4, there are non-classical intramolecular C—H⋯N hydrogen bonds and intermolecular C—H⋯π interactions. [ABSTRACT FROM AUTHOR]

The title compound, C12H16N4O4S, is composed of two substituted pyrazole rings, which are connected through a sulfone group. The dihedral angle between the two pyrazole rings is 79.1 (1)°. The ethoxy­carbonyl substituent is planar and is slightly twisted away from the attached pyrazole ring. [ABSTRACT FROM AUTHOR]

The tetra­hydro­pyrimidine ring of the title mol­ecule, C11H11FN2OS, adopts a half-chair conformation. In the crystal structure, the mol­ecules are linked to form centrosymmetric hydrogen-bonded dimers. [ABSTRACT FROM AUTHOR]

In the title compound, C18H18ClN5O2, there are two independent mol­ecules in the asymmetric unit. In both mol­ecules, the pyrimidine ring is almost coplanar with the central pyrazole ring, while the benzene ring is almost perpendicular to it. [ABSTRACT FROM AUTHOR]

The title mol­ecule, C17H25N5O3S2, belongs to the family of bis-heterocycles. In the crystal structure, there are one intra- and two inter­molecular hydrogen bonds. One of the two pyrazole rings and the six-membered ring formed by the intra­molecular hydrogen bond are approximately coplanar. [ABSTRACT FROM AUTHOR]

The crystal structure of the title compound, C18H20N6O3, is stabilized by N—H⋯O and N—H⋯N hydrogen bonds. [ABSTRACT FROM AUTHOR]

The title compound, C11H9ClN2O2, crystallizes with weak inter­molecular N—H⋯O hydrogen-bond inter­actions. The dihedral angle between the pyrimidine and benzene rings is 86.82 (7)°. [ABSTRACT FROM AUTHOR]