AgSbF6-Mediated Selective Thiolation and Selenylation at C-4 Position of Isoquinolin-1(2 H)-ones.

A new and facile AgSbF6-mediated protocol for the construction of C-4 thiolated or selenylated isoquinolin-1(2 H)-ones via a radical pathway was established. This reaction proceeded efficiently with excellent regioselectivity, a broad substrate scope, and good functional group tolerance. A radical reaction mechanism involving thiyl radicals as key intermediates is proposed for the present transformation.

Novel HPPD inhibitors: triketone 2H-benzo[b][1,4]oxazin-3(4H)-one analogs.

BACKGROUND: Herbicides that inhibit 4-hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27) are very important for grass weed control. In order to discover novel HPPD herbicides, a series of triketone 2H-benzo[b] oxazin-3(4H)-one analogs was designed and synthesized. RESULTS: In comparison with the commercial triketone HPPD herbicide mesotrione (IC50 = 0.252 µM), some of these new triketone analogs displayed excellent HPPD inhibitory potency in vitro, for example B39 (IC50 = 0.172 µM) and B41 (IC50 = 0.156 µM). In addition, some of these compounds exhibited pre- and post-emergence herbicidal activity similar to mesotrione when applied at 375 g/ha. CONCLUSION: Many of the title compounds described in this paper could be important lead structures for the further development of novel HPPD herbicides. © 2017 Society of Chemical Industry.

Route to Substituted Furan-2(5H)-ones from cyclo-Alkenecarboxylic Acids and Acrylates via C-H Activation.

Under rhodium(III) catalysis, four kinds of cycloalkenecarboxylic acids successfully reacted with acrylates via direct activation of the ß-alkenyl C-H bond. The present protocol provides the facile and highly efficient synthesis of substituted furan-2(5H)-ones from readily available starting materials with moderate to good yields. In addition, their possible reaction mechanisms were also discussed.

Synthesis and herbicidal activities of novel 3-(substituted benzyloxy or phenoxy)-6-methyl-4-(3-trifluoromethylphenyl)pyridazine derivatives.

BACKGROUND: 4-(3-Trifluoromethylphenyl)pyridazine represents a new series of compounds with bleaching and herbicidal activities. RESULTS: A total of 43 novel 3-(substituted benzyloxy or phenoxy)-6-methyl-4-(3-trifluoromethylphenyl)pyridazine derivatives were synthesised, and their bleaching and herbicidal activities were evaluated through Spirodela polyrrhiza and greenhouse tests. Some compounds exhibited excellent herbicidal activities, even at a dose of 7.5 g ha(-1). CONCLUSION: The results showed that a substituted phenoxy group at the 3-position of the pyridazine ring and the electron-withdrawing group at the para-position on the benzene ring were essential for high herbicidal activity.

(4Z)-4-[(Cyclo-propyl-amino)(phen-yl)methyl-ene]-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one.

In the title compound, C(20)H(19)N(3)O, the dihedral angles formed by the pyrazolone ring with the two phenyl rings are 64.27 (6) and 17.00 (6)°. The mol-ecular structure is stabilized by intra-molecular N-H⋯O and C-H⋯O hydrogen bonds. In the crystal, the mol-ecules are linked into chains along the b axis by inter-molecular C-H⋯O hydrogen bonds.

4-[(Z)-Allyl-amino-(phen-yl)methyl-ene]-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one.

The title compound, C(20)H(19)N(3)O, exists in a keto-enamine tautomeric form. The pyrazolone ring makes dihedral angles of 20.52 (10) and 77.73 (5)° with the two phenyl rings and an intra-molecular N-H⋯O hydrogen bond occurs. A weak inter-molecular C-H⋯O hydrogen bond is observed in the crystal structure. The allyl group is disordered over two positions, with site-occupancy factors of 0.533 (5) and 0.467 (5).

1-sec-Butyl-3-[hy-droxy(1-methyl-1H-indol-3-yl)methyl-idene]pyrrolidine-2,4-dione.

In the title compound, C(18)H(20)N(2)O(3), the dihedral angle between the indole ring system (r.m.s. deviation = 0.018 Å) and the hy-droxy-methyl-enepyrrolidine-2,4-dione plane (r.m.s. deviation = 0.036 Å) is 9.87 (7)°. The keto and enol groups are involved in an intra-molecular O-H⋯O hydrogen bond. An intra-molecular C-H⋯O inter-action also occurs. The sec-butyl group is disordered over two orientations corresponding to an approximate 180° rotation about the N-C bond, with occupancies of 0.670 (6) and 0.330 (6). In the crystal, mol-ecules are linked into chains along the c axis by C-H⋯O hydrogen bonds.

(Z)-3-[(4-Eth-oxy-phen-yl)(hy-droxy)methyl-idene]-1-isopropyl-pyrrolidine-2,4-dione.

In the title compound, C(16)H(19)NO(4), a potent new herbicide, the dihedral angle between the benzene and pyrrolidine rings is 11.09 (8)°. Intra-molecular O-H⋯O and C-H⋯O hydrogen bonds are observed.

4-{(Z)-(sec-Butyl-amino)(phen-yl)methyl-ene}-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one.

In the title compound, C(21)H(23)N(3)O, the dihedral angles formed by the pyrazolone ring with two phenyl rings are 10.38 (8) and 76.94 (6)°. The sec-butyl-amino group is disordered over two positions, with refined site-occupancy factors of 0.730 (4) and 0.270 (4). The compound could potentially be ligand stabilized in the solid state in a keto-enamine tautomeric form. The amine functionality is involved in an intra-molecular N-H⋯O hydrogen bond, while weak inter-molecular C-H⋯O and C-H⋯N hydrogen bonds participate in the formation of the crystal structure.

(4Z)-4-[(4-Methoxy-benzyl-amino)(phen-yl)methyl-ene]-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one.

In the title compound, C(25)H(23)N(3)O(2), the dihedral angles formed by the pyrazolone ring with the three aromatic rings are 14.59 (7), 79.35 (5) and 87.10 (6)°. Three intra-molecular C-H⋯O, C-H⋯N and N-H⋯O hydrogen-bond inter-actions are present. The crystal structure is stabilized by two weak inter-molecular C-H⋯O and C-H⋯N hydrogen-bond inter-actions.

Novel protoporphyrinogen oxidase inhibitors: 3H-pyrazolo[3,4-d][1,2,3]triazin-4-one derivatives.

A series of 3 H-pyrazolo[3,4-d][1,2,3]triazin-4-one derivatives were synthesized as candidate herbicides by diazotization of different 5(3)-amino- N-phenyl-1 H-pyrazole-4-carboxamide derivatives prepared by the reaction of substituted 5(3)-amino-pyrazole-4-carbonyl chloride with a substituted aniline. Their structures were identified by (1)H NMR and elemental analyses. The isomers D and E were isolated, and their structures were identified by two-dimensional NMR analyses (heteronuclear single quantum coherence and heteronuclear multiple-bond correlation) and single-crystal X-ray diffraction analysis. The bioassay results showed that some of the title compounds exhibited both excellent herbicidal activity at a dose of 93.75 g/ha and strong inhibition against protoporphyrinogen oxidase activity in vitro. The structure-activity relationship showed that D16 possessed the highest activities both in vivo and in vitro when the N-substituted group of the pyrazole ring was allyl and the N-substituted group of benzooxazinone was propargyl.

Synthesis and herbicidal activities of novel 3-N-substituted amino-6-methyl-4-(3-trifluoromethylphenyl)pyridazine derivatives.

4-(3-Trifluoromethylphenyl)pyridazine is a new series of compounds with bleaching and herbicidal activities. Starting from ethyl 2-(3-trifluoromethylphenyl)acetate, an important intermediate 7 was synthesized in five steps with a moderate total yield of 51.5% in a safe and practical way. Twenty-six novel 3-N-substituted amino-6-methyl-4-(3-trifluoromethylphenyl)pyridazine derivatives were synthesized and evaluated through a Spirodela polyrrhiza test and greenhouse test. Some compounds can completely inhibit Chl at 1 microg/mL and exhibit equal or higher herbicidal activities with the commercial bleaching herbicide diflufenican against dicotyledonous plants at a rate of 75 g/ha.

4-[3-(Trifluoro-meth-yl)phen-yl]-5,6,7,8-tetra-hydro-cinnolin-3(2H)-one.

The title compound, C(15)H(13)F(3)N(2)O, contains one benzene ring, one cyclo-hexane 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 inter-molecular hydrogen bonds (N-H⋯O and C-H⋯F). The cyclohexane ring adopts a screw-boat conformation. The CF(3) group is disordered over two positions; the site occupancy factors are ca 0.6 and 0.4.

6-Methyl-2-p-tolyl-4-[3-(trifluoro-meth-yl)phen-yl]pyridazin-3(2H)-one.

In the title mol-ecule, C(19)H(15)F(3)N(2)O, the benzene rings of the tolyl and trifluoro-methyl-phenyl groups form dihedral angles of 64.1 (2) and 38.5 (2)°, respectively, with the pyridazine ring. The CF(3) group is disordered over two orientations, with site-occupancy factors of ca 0.56 and 0.44.

Methyl 3-(4-{6-methyl-4-[3-(trifluoro-meth-yl)phen-yl]pyridazin-3-yl-oxy}phen-yl)propanoate.

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.

Design, synthesis, and quantitative structure-activity relationship study of herbicidal analogues of pyrazolo[5,1-d][1,2,3,5]tetrazin-4(3H)ones.

A series of pyrazolo[5,1-d][1,2,3,5]tetrazin-4(3H)one derivatives were designed, synthesized, and evaluated for their herbicidal activities where some of these compounds provided >80% control of Brassica campestris at 10 microg/mL. Quantitative structure-activity relationship studies were performed on these compounds using physicochemical parameters (electronic, Verloop, or hydrophobic) as independent parameters and herbicidal activity as a dependent parameter, where herbicidal activity correlated best (r > 0.8) with physicochemical parameters in this set of molecules. The herbicidal activity against B. campestris was mainly affected by the molar refractivity (MR) for R1, Taft (Eso) for R2 or R6, Verloop (Lm) for R3 or R5, and electronic parameters (Hammett's constants) for R4. The optimal MR for herbicidal activity is 0.95. The herbicidal activity against Echinochloa crus-galli was mainly related with the substituents' hydrophobic parameter. The optimal pi parameters for R1 and R4 for herbicidal activity are 0.72 and 0.68, respectively. In general, these compounds showed greater herbicidal activity toward B. campestris than E. crus-galli.

tert-Butyl 4-({[(E)-1,3-dimethyl-5-phen-oxy-pyrazol-4-yl]meth-yl}amino-oxymeth-yl)benzoate.

The title compound, C(24)H(27)N(3)O(4), also known as fenpyroximate, is a commercial acaricide. The benzene ring of the phen-oxy group is approximately perpendicular to the pyrazole ring with a dihedral angle of 84.37 (11)°. The dihedral angle between the phen-oxy and the benzoate benzene rings is 48.83 (8)°.

3-[(Hydr-oxy)(4-isoprop-oxy-2-methoxy-phen-yl)methyl-ene]-1-isopropyl-pyrrol-idine-2,4-dione.

The title compound, C(18)H(23)NO(5), a potential herbicide, has an enol group that is intra-molecularly hydrogen bonded to a keto O atom. The dihedral angle between the six-membered ring formed by the enol group and the aromatic benzene ring is 53.35 (6)°.

A quantitative structure-activity relationship study of herbicidal analogues of alpha-hydroxy-substituted 3-benzylidenepyrrolidene-2,4-diones.

A series of pyrrolidine-2,4-dione and piperidine-2,4-dione derivatives were prepared and evaluated for their herbicidal activities where some of these compounds exhibited good bioactivity against Echinochloa crus-galli in comparison with sulcotrione. Quantitative structure-activity relationship studies were performed on these compounds using physicochemical parameters (hydrophobic, electronic, and Taft) as independent parameters and herbicidal activity as a dependent parameter, where herbicidal activity correlated best (r > 0.8) with hydrophobic (pi(o) + pi(p)), steric (Es), STERIMOL (B4), indicator (H(M)), van der Waals volume (V), and electronic parameter (sigma(m) + sigma(p)) in this set of molecules; the optimum van der Waals volume for R(2) is about 41.8 A3; when B4 is equal to 3, the target molecule possessed the lowest herbicidal activity.