Study on Design, Synthesis and Herbicidal Activity of Novel 6-Indazolyl-2-picolinic Acids.

Thirty-eight new 4-amino-3,5-dicholo-6-(1H-indazolyl)-2-picolinic acids and 4-amino-3,5-dicholo-6-(2H-indazolyl)-2-picolinic acids were designed by scaffold hopping and synthesized to discover potential herbicidal molecules. All the new compounds were tested to determine their inhibitory activities against Arabidopsis thaliana and the root growth of five weeds. In general, the synthesized compounds exhibited excellent inhibition properties and showed good inhibitory effects on weed root growth. In particular, compound 5a showed significantly greater root inhibitory activity than picloram in Brassica napus and Abutilon theophrasti Medicus at the concentration of 10 µM. The majority of compounds exhibited a 100% post-emergence herbicidal effect at 250 g/ha against Amaranthus retroflexus and Chenopodium album. We also found that 6-indazolyl-2-picolinic acids could induce the up-regulation of auxin genes ACS7 and NCED3, while auxin influx, efflux and auxin response factor were down-regulated, indicating that 6-indazolyl-2-picolinic acids promoted ethylene release and ABA production to cause plant death in a short period, which is different in mode from other picolinic acids.

Design, Synthesis, Fungicidal and Insecticidal Activities of Novel Diamide Compounds Combining Pyrazolyl and Polyfluoro-Substituted Phenyl into Alanine or 2-Aminobutyric Acid Skeletons.

Thirty novel diamide compounds combining pyrazolyl and polyfluoro-substituted phenyl groups into alanine or 2-aminobutyric acid skeletons were designed and synthesized with pyflubumide as the lead compound to develop potent and environmentally friendly pesticides. The preliminary bioassay results indicated that the new compounds containing the para-hexa/heptafluoroisopropylphenyl moiety exhibit fungicidal, insecticidal, and acaricidal activities. This is the first time that the para-hexa/heptafluoroisopropylphenyl group is a key fragment of the fungicidal activity of new N-phenyl amide compounds. Most of the target compounds exhibited moderate to good insecticidal activity against Aphis craccivora at a concentration of 400 µg/mL, and some showed moderate activity at a concentration of 200 µg/mL; in particular, compounds I-4, II-a-10, and III-26 displayed higher than 78% lethal rates at 200 µg/mL. Compound II-a-14 exhibited a 61.1% inhibition at 200 µg/mL for Tetranychus cinnabarinus. In addition, some of the target compounds exhibited good insecticidal activities against Plutella xylostella at a concentration of 200 µg/mL; the mortalities of compounds I-1, and II-a-15 were 76.7% and 70.0%, respectively. Preliminary analysis of the structure-activity relationship (SAR) indicated that the insecticidal and acaricidal activities varied significantly depending on the type of substituent and substitution pattern. The fungicidal activity results showed that compounds I-1, II-a-10, II-a-17, and III-26 exhibited good antifungal effects. Enzymatic activity experiments and in vivo efficacy of compound II-a-10 were conducted and discussed.

Design, Synthesis, Herbicidal Activity, and Structure-Activity Relationship Study of Novel 6-(5-Aryl-Substituted-1-Pyrazolyl)-2-Picolinic Acid as Potential Herbicides.

Picolinic acid and picolinate compounds are a remarkable class of synthetic auxin herbicides. In recent years, two new picolinate compounds, halauxifen-methyl (ArylexTM active) and florpyrauxifen-benzyl (RinskorTM active), have been launched as novel herbicides. Using their structural skeleton as a template, 33 4-amino-3,5-dicholor-6-(5-aryl-substituted-1-pytazolyl)-2-picolinic acid compounds were designed and synthesized for the discovery of compounds with potent herbicidal activity. The compounds were tested for inhibitory activity against the growth of Arabidopsis thaliana roots, and the results demonstrated that the IC50 value of compound V-7 was 45 times lower than that of the halauxifen-methyl commercial herbicide. Molecular docking analyses revealed that compound V-7 docked with the receptor auxin-signaling F-box protein 5 (AFB5) more intensively than picloram. An adaptive three-dimensional quantitative structure-activity relationship model was constructed from these IC50 values to guide the next step of the synthetic strategy. Herbicidal tests of the new compounds indicated that compound V-8 exhibited better post-emergence herbicidal activity than picloram at a dosage of 300 gha-1, and it was also safe for corn, wheat, and sorghum at this dosage. These results demonstrated that 6-(5-aryl-substituted-1-pyrazolyl)-2-picolinic acid compounds could be used as potential lead structures in the discovery of novel synthetic auxin herbicides.

Design, Synthesis, and Biological Activities of Novel 1,3,5-Trimethylpyrazole-Containing Malonamide Derivatives.

New 1,3,5-trimethylpyrazole-containing malonamide derivatives based on pyflubumide were designed, synthesized, and characterized using ¹H-NMR, 13C-NMR, and high-resolution mass spectra (HRMS). The results of preliminary bioassays showed that the target compounds possessed good activities against Tetranychus cinnabarinus, Plutella xylostella, and Aphis craccivora. Most of the target compounds exhibited moderate to good acaricidal activity against Tetranychus cinnabarinus at a concentration of 400 µg/mL, and some showed moderate activity at a concentration of 200 µg/mL; in particular, compounds 8m and 8p exhibited 70.0% mortality. In addition, some of the target compounds exhibited good insecticidal activities against Plutella xylostella at a concentration of 200 µg/mL, especially compounds 8i and 8o, which achieved 100.0% mortality at a concentration of 100 µg/mL. Interestingly, some of the target compounds exhibited potent anti-aphid activity against Aphis craccivora at a concentration of 200 µg/mL; furthermore, compounds 8p and 8q demonstrated 100.0% anti-aphid activity at a concentration of 50 µg/mL. The preliminary analyses of the structure⁻activity relationships (SAR) indicated that the acaricidal and insecticidal activities varied significantly depending on the type of substituent and substitution pattern, which provides guidance for the further investigation of such structural modifications.

A one-pot approach to pyridyl isothiocyanates from amines.

A one-pot preparation of pyridyl isothiocyanates (ITCs) from their corresponding amines has been developed. This method involves aqueous iron(III) chloride-mediated desulfurization of a dithiocarbamate salt that is generated in situ by treatment of an amine with carbon disulfide in the present of DABCO or sodium hydride. The choice of base is of decisive importance for the formation of the dithiocarbamate salts. This one-pot process works well for a wide range of pyridyl ITCs. Utilizing this protocol, some highly electron-deficient pyridyl and aryl ITCs are obtained in moderate to good yields.

[Physical stability of imidacloprid suspension concentrate studied by the multiple light scattering technique].

The stability of pesticide SC suspension was studied by Turbiscan Lab Analyzer. The Turbiscan Lab can be used to analyze the concentrated colloids, dispersant samples, and the instable mechanism of the suspension system in the initial stage. The Turbiscan Lab can also determine the thickness changes of sedimentation with the time, the settling rate of particles with time, and the particle size changes with time. In the present work, the different dispersant GY-D10, NNO, Morwet D-425, TERSPERSE 2425 were used to prepare the imidacloprid 350 g x L(-1) suspension concentrate in the same preparation condition. By measuring the light intensity of backscattering light of the suspension of imidacloprid 350 g x L(-1) SC with time, the dynamic sedimentation processes and the particle size changes which reflect the stability of SC suspension were studied. The results showed that when the contents of GY-D10 dispersant were 4 wt% in the SC, the stability of SC suspension system was relatively good.

Parallel kinetic resolution of aziridines via chiral phosphoric acid-catalyzed apparent hydrolytic ring-opening.

We report a chiral phosphoric acid catalyzed apparent hydrolytic ring-opening reaction of racemic aziridines in a regiodivergent parallel kinetic resolution manner. Harnessing the acyloxy-assisted strategy, the highly stereocontrolled nucleophilic ring-opening of aziridines with water is achieved. Different kinds of aziridines are applicable in the process, giving a variety of enantioenriched aromatic or aliphatic amino alcohols with up to 99% yields and up to >99.5 : 0.5 enantiomeric ratio. Preliminary mechanistic study as well as product elaborations were inducted as well.

Highly enantioselective addition of 1,3-diynes to aldehydes catalyzed by a zinc-amino alcohol complex.

Asymmetric catalysis: A highly enantioselective and efficient procedure for the amino alcohol-zinc-catalyzed addition of 1,3-diynes to various aromatic, α,ß-unsaturated, and aliphatic aldehydes has been developed. The present catalytic system was successfully applied in the concise synthesis of natural products such as (S)-strongylodiols A and B (see scheme).

Development of an enzyme-linked immunosorbent assay specific to Sudan red I.

To obtain antibodies to develop an enzyme-linked immunosorbent assay (ELISA) for the analysis of Sudan red I, haptens were designed and synthesized via four different strategies: (i) attachment of a spacer at the para position of the benzene ring, (ii) attachment of a spacer at the naphthol part, (iii) attachment of a spacer at the hydroxyl group of the Sudan red I molecule, and (iv) use of a fragment of the target molecule. A total of 10 haptens were used to generate immunogens, coating antigens, and polyclonal antibodies. One of the heterologous ELISAs developed exhibited an IC(50) of 1.6 ng/ml, a limit of detection (LOD) of 0.03 ng/ml, and a dynamic range between 0.1 and 14 ng/ml. The assay had 13% cross-reactivity with Para red and negligible cross-reactivity with other structure-related compounds. This ELISA was much more specific than those published previously. This assay was used to determine Sudan red I residues in tomato sauce and chili powder samples after simple pretreatment. The results were validated by comparison with high-performance liquid chromatography (HPLC). The average recoveries of Sudan red I by ELISA and HPLC were in ranges of 70-97% and 82-114%, respectively, indicating suitability of the developed ELISA for screening of Sudan red I in foods.

Highly enantioselective zinc/amino alcohol-catalyzed alkynylation of aldehydes.

Meeting the challenge: The zinc/amino alcohol catalyzed enantioselective addition of terminal alkynes to aldehydes is effective with both phenylacetylene and methyl propiolate, leading to chiral secondary propargyl alcohols with very high enantioselectivity (see scheme).

A highly sensitive and selective immunoassay for the detection of tetrabromobisphenol A in soil and sediment.

Tetrabromobisphenol A is the most widely used brominated flame retardant. A sensitive and selective enzyme-linked immunosorbent assay (ELISA) for the detection of tetrabromobisphenol A was developed. The limit of detection and the inhibition half-maximum concentration of tetrabromobisphenol A in phosphate buffered saline with 10% methanol were 0.05 and 0.87 ng mL(-1), respectively. Cross-reactivity values of the ELISA with a set of important brominated flame retardants including tetrabromobisphenol A-bis(2,3-dibromopropylether), 2,2',6,6'-tetrabromobisphenol A diallyl ether, hexabromocyclododecane, 1,2-bis(pentabromodiphenyl) ethane, 1,2-bis(2,4,6 tribromophenoxy) ethane, bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate, 2-ethylhexyl-2,3,4,5-tetrabromobenzoate, and polybrominated diphenyl ethers were <0.05%. Concentrations of tetrabromobisphenol A determined by ELISA in the soils from farmlands, the soils from an e-waste recycling site, and the sediments of a canal were in the range of non-detectable-5.6 ng g(-1), 26-104 ng g(-1) and 0.3-22 ng g(-1)dw, respectively, indicating the ubiquitous pollution of tetrabromobisphenol A. The results of this assay for 16 real world samples agreed well with those of the liquid chromatography-tandem mass spectrometry method, indicating this ELISA is suitable for screening of tetrabromobisphenol A in environmental matrices.

Design, synthesis, and insecticidal activities of phthalamides containing a hydrazone substructure.

Fluobendiamide is the first commercialized artificial synthetic insecticide acting on the ryanodine receptor. This new molecule possesses a combination of excellent insecticidal activity and eco-friendly characteristics with a skeleton structure of phthalamide. In this study, we incorporated hydrazone, present in many pesticidal compounds reported during the last two decades, into phthalamide derivatives via Schiff-base condensation and aminolysis to obtain 21 new compounds; these compounds were characterized by proton nuclear magnetic resonance ((1)H NMR), infrared spectroscopy (IR), and high-resolution mass spectrometry (HRMS) or elemental analysis. A preliminary bioassay against peach aphids ( Myzus persicae ) revealed that the title compounds exhibited good stomach toxicity at 600 mg/L. Twelve new compounds were found to display higher activity than postive control flubendiamide (LC(50) = 184.099 mg/L), however, LC(50) was less than 100 mg/L only for compounds 4e, 4o, 4s, 4t (59-77 mg/L). That is, combinations of a p-fluorophenyl or (methyl)thienyl group at the Ar position with an isopropyl or cyclohexyl group at the R position might improve the lethality of the designed phthalamide derivative. Preliminary results of a bioassay at 600 mg/L against diamondback moth ( Plutella xylostella , Linnaeus) showed that only the title compound 4e possessed good larvicidal activity. On comparison of the bioassay results of stomach toxicity and larvicidal activity, it is noteworthy that the compound incorporating phenylpyrazolyl exhibited good larvicidal activity and poor stomach activity.

Liquid-phase synthesis of chiral tartrate ligand library for enantioselective sharpless epoxidation of allylic alcohols.

This paper reports a successful development of a group of efficient soluble polymer-supported chiral tartrate ligands by liquid-phase synthesis for Sharpless epoxidation of a variety of allylic alcohols through ligand diversity. The influence of substituent in chiral tartrate ligands on the enantioselectivities of the reaction was disclosed. Moderate chemical yields and good enantiomeric excesses were obtained by using soluble polymer-supported tartrate ester in the epoxidation of allylic alcohols with Ti(O-i-Pr)(4)/tert-butyl hydroperoxide.