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In this paper, both 1,4-dihydropyridinones (Hantzsch products) and 3,4-dihydropyrimidinones (Biginelli products) are synthesized in one-pot of aldehydes, β-dicarbonyl compounds and urea, catalyzing by non-toxic room temperature ionic liquid 1-n-butyl-3-methylimidazolium saccharinate (BMImSac). The ionic liquid (BMImSac) is environmentally benign associated with ionic liquid with F−. In order to improve the yield and selectivity, the effects of the mole proportion of reactants and solvents are investigated. Interestingly, by increasing the amount of ethyl acetoacetate or utilizing water as solvent, an unexpected by-product, Hantzsch product which is distinct from Biginelli product, is generated. All Biginelli and Hantzsch products are simultaneously purified and characterized by IR, 1H NMR and 13C NMR, of which one Biginelli product (4h) and one Hantzsch product (5b) are structurally determinated by X-ray single crystal diffraction. The crystal data for 4h: triclinic system, P-1 space group, a = 7.515(3) A, b = 9.011(4) A, c = 11.218(5) A, α = 106.288(6)°, β = 104.644(6)°, γ = 100.234(6)°, Z = 2, V = 679.7(5) A3, Dc = 1.36 g/cm3, R1 = 0.0603. The crystal data for 5b: monoclinic system, P2(1)/c space group, a = 9.765(3) A, b = 7.391(2) A, c = 24.795(7) A, β = 93.669(5)°, Z = 4, V = 1785.7(9) A3, Dc = 1.292 g/cm3, R1 = 0.0440.

Ethyl 5-amino-3-trifluoromethyl-1H-pyrazole-4-carboxylate (1) was efficiently synthesized via the condensation of ethyl cyanoacetate and trifluoroacetic anhydride, followed by chloridization and the condensation with aqueous hydrazine. Its unique reactivity was exploited for the synthesis of trifluoromethylated pyrazolo[1,5-a]pyrimidine (5) and pyrazolo[5,1-d][1,2,3,5]tetrazine-4(3H)-ones (8a–j). Among them, 5 was firstly found to be a novel fluorescent molecule that might be exploited as an attractive fluorophore for possessing many binding sites, and its fluorescence intensity was obviously stronger than its methyl analogue. 8 were found to be a new chemical class of potential monocotyledonous Echinochloa crus-galli L. Beauv inhibitors, and were more active than their methyl analogues.

A series of novel alpha,alpha,alpha-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 microg 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).

A series of new 2-aryl-7-cyano/ethoxycarbonyl-6-methylthio-1H-imidazo[1,2-b]pyrazoles (5) have been synthesized in moderate to good yields, via a two-step cyclocondensation procedure of 5-amino-4-cyano/ethoxycarbonyl-3-methylthio-1H-pyrazole (1) and α-bromoacetophenones (3) or α-tosyloxyacetophenones (2), which were prepared by the reactions of acetophenones with [hydroxy(tosyloxy)iodo]benzene (HTIB). The intermediates, 5-amino-1-(aroylmethyl)-4- cyano/ethoxycarbonyl-3-methylthio-1H-pyrazoles (4), have been isolated, serving as evidence for the regioselectivity. When utilizing α-tosyloxy-acetophenones, the reactions were more eco-friendly, the reaction time was significantly reduced and the synthetic procedure was more convenient and easier to manipulate. Surprisingly, using potassium carbonate to displace sodium carbonate in the synthesis of 4, in the case of 1 (R CN), two novel cyclocondensation products have been isolated and fully characterized, followed by the proposal of a plausible mechanism.

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-tetrahydropyrimidin-1-yl]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)/89.75 (11), 89.13 (9) and 87.52 (13) degrees , 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)/11.953 (6), 10.734 (10) and 10.889 (9) A, respectively. In all three crystal structures, the molecules are linked to generate sheets of molecules via C-H...O interactions.

The crystal structure of the title compound, C18H20N6O3, is stabilized by N—H...O and N—H...N hydrogen bonds.

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.

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.

The tetra­hydro­pyrimidine ring of the title mol­ecule, C11H11ClN2OS, adopts a half-chair conformation. In the crystal structure, the mol­ecules are linked to form centrosymmetric hydrogen-bonded dimers.

The title compound, C15H17NO4, is a potent new herbicide containing the pyrrolidine-2,4-dione ring system. In the crystalline state, the molecular skeleton contains one enol grouping, which is intramolecularly hydrogen bonded to a neighboring keto O atom.

In the title compound, C(22)H(19)F(3)N(2)O(3), the benzene rings of the trifluoro-methyl-phenyl and benzoyl-phenyl groups form dihedral angles of 41.89 (10) and 67.44 (10)°, respectively, with the pyridazine ring. The methyl-propanoate group is nearly coplanar with the attached benzene ring [dihedral angle = 3.9 (2)°]. The trifluoro-methyl group is disordered over two positions; the site-occupancy factors are ca 0.64 and 0.36. In the crystal structure, inversion-related mol-ecules are linked through C-H⋯O hydrogen bonds and C-H⋯π inter-actions.

A series of 2-(3-(trifluoromethyl)-5-(alkoxy)-1H-pyrazol-1-yl)-4-aryloxypyrimidine derivatives were designed and synthesized. The structures of all the title compounds were confirmed by 1H NMR and elementary analysis. These compounds were screened for herbicidal activity against rape and barnyard grass. Compound B13 exhibited moderate herbicidal activity.

Ethyl 5-amino-3-trifluoromethyl-1H-pyrazole-4-carboxylate (1) was efficiently synthesized via the condensation of ethyl cyanoacetate and trifluoroacetic anhydride, followed by chloridization and the condensation with aqueous hydrazine. Its unique reactivity was exploited for the synthesis of trifluoromethylated pyrazolo[1,5-a]pyrimidine (5) and pyrazolo[5,1-d][1,2,3,5]tetrazine-4(3H)-ones (8a–j). Among them, 5 was firstly found to be a novel fluorescent molecule that might be exploited as an attractive fluorophore for possessing many binding sites, and its fluorescence intensity was obviously stronger than its methyl analogue. 8 were found to be a new chemical class of potential monocotyledonous Echinochloa crus-galli L. Beauv inhibitors, and were more active than their methyl analogues.

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.

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.

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)°.

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.

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

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.

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.

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)°.