Discovery of pyridine-based agrochemicals by using Intermediate Derivatization Methods.

Pyridine-based compounds have been playing a crucial role as agrochemicals or pesticides including fungicides, insecticides/acaricides and herbicides, etc. Since most of the agrochemicals listed in the Pesticide Manual were discovered through screening programs that relied on trial-and-error testing and new agrochemical discovery is not benefiting as much from the in silico new chemical compound identification/discovery techniques used in pharmaceutical research, it has become more important to find new methods to enhance the efficiency of discovering novel lead compounds in the agrochemical field to shorten the time of research phases in order to meet changing market requirements. In this review, we selected 18 representative known agrochemicals containing a pyridine moiety and extrapolate their discovery from the perspective of Intermediate Derivatization Methods in the hope that this approach will have greater appeal to researchers engaged in the discovery of agrochemicals and/or pharmaceuticals.

Synthesis and evaluation of substituted 3-(pyridin-2-yl)benzenesulfonamide derivatives as potent herbicidal agents.

In an attempt to obtain novel candidate compound for weed control, a series of newly substituted 3-(pyridin-2-yl)benzenesulfonamide derivatives 2 were designed and synthesized using compound II7 as a lead compound by Intermediate Derivatization Methods and their herbicidal activities were evaluated. The herbicidal activity assay in greenhouse tests showed several compounds (2g, 2i, 2j, 2k, 2l, 2m, 2n and 2o) exhibited significant herbicidal activity for controlling velvet leaf (Abutilon theophrasti medic.) and youth-and-old age (Zinnia elegans jacq.

Design, synthesis, and herbicidal activity of novel substituted 3-(pyridin-2-yl)benzenesulfonamide derivatives.

A series of novel substituted 3-(pyridin-2-yl)benzenesulfonamide derivatives were designed and synthesized using 2-phenylpridines as the lead compound by intermediate derivatization methods in an attempt to obtain novel compound candidates for weed control. The herbicidal activity assay in glasshouse tests showed several compounds (II6, II7, II8, II9, II10, II11, III2, III3, III4, and III5) could efficiently control velvet leaf, youth-and-old age, barnyard grass, and foxtail at the 37.5 g/ha active substance.

Design, synthesis, and structure-activity relationship of novel aniline derivatives of chlorothalonil.

Chlorothalonil with both low cost and low toxicity is a popularly used fungicide in the agrochemical field. The presence of nucleophilic groups on this compound allows further chemical modifications to obtain novel chlorothalonil derivatives. Fluazinam, another commercially available agent with a broad fungicidal spectrum, has a scaffold of diaryl amine structure.

Synthesis and bioactivity of novel coumarin derivatives.

A series of coumarin derivatives (6-8) containing (E)-methyl 2-(methoxyimino)-2-phenylacetate, (E)-2-(methoxyimino)-N-methyl-2-phenylacetamide and methyl methoxy(phenyl)carbamate were synthesized from substituted resorcinols (1) and substituted beta-keto esters (2) as starting material via cyclization and condensation reactions. The test results indicated that (E)-methyl 2-{2-[(3-hexyl-4-methyl-coumarin-7-yloxy)methyl]phenyl}-2-(methoxyimino)acetate (6f) was the optimal structure with good fungicidal activity against cucumber grey mold (CGM) giving 100% control at 100 mg L(-1) concentration, much higher than that of coumoxystrobin. Methyl 2-[(3,4-dimethyl-coumarin -7-yloxy)methyl]phenyl(methoxy)carbamate (8a) was another optimal structure with good fungicidal activity against wheat powdery mildew (WPM) showing 100% control at 50 mg L(-1) concentration, at the same level as that of the commercial kresoxim-methyl, and very significantly higher than that of coumoxystrobin (no control against WPM at 400 mg L(-1)).

Design, synthesis and structure-activity relationship of novel coumarin derivatives.

Background: The lead coumarin derivative (E)-methyl 3-methoxy-2-[2-(4-methylcoumarin-7-yloxymethyl)phenyl]acrylate was discovered by using an intermediate derivatisation method. To discover new coumarin derivatives with improved activity, a series of substituted coumarins were synthesised and bioassayed.

Results: The compounds were identified by ¹H NMR, IR, MS and elemental analysis.