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 fungicidal activity of novel strobilurin analogues containing substituted N-phenylpyrimidin-2-amines.

A series of novel compounds (5-8) was designed and synthesized by integrating the active pharmacophore of the N-phenylpyrimidin-2-amine fungicide with the structure of strobilurin fungicide. The rationale of this approach was to determine if these new compounds exhibit unique biological activity (selectivity and potency) compared with the commercial standards. The title compounds were prepared from 2-(phenylamino)pyrimidin-4-ols (3) by treatment with one equivalent of intermediates (4) containing strobilurin pharmacophores. 2-(Phenylamino)pyrimidin-4-ols (3) were in turn prepared from phenylguanidines (1) and substituted beta-ketoesters (2). Biological activities evaluated in the greenhouse indicated that compounds 5a, 6a and 7a have good fungicidal activity at 25 mg/L, comparable with that of the commercial standards, cyprodinil and azoxystrobin.

Design, synthesis and biological activity of new strobilurin derivatives with a 1H-pyrazol-5-oxy side chain.

A series of new strobilurin derivatives with a substituted pyrazole side chain (5 and 6) were designed and synthesized. The new derivatives were synthesized from substituted phenones as starting material via esterification, cyclization and condensation reactions. All compounds were identified by 1H NMR and IR spectral and elemental analyses. Preliminary biological evaluation showed that some of the compounds had good fungicidal activity against cucumber downy mildew (CDM) and wheat powdery mildew (WPM) at 6.25 and 1.56 mg L(-1), respectively. Some of the compounds showed insecticidal activity against armyworm (AW), green peach aphid (GPA) and culex mosquitoes at 600 mg L(-1).