Synthesis of novel 26-substituted milbemycin A4 derivatives and their acaricidal activities.

A series of novel 26-substituted milbemycin A4 derivatives was synthesized from 5-O-t-butyldimethylsilyl-26-hydroxymilbemycin A4 prepared by selenium dioxide oxidation of 5-O-t-butyldimethylsilyl-milbemycin A4. Their acaricidal activities were assessed against the organophosphorus-sensitive two-spotted spider mite (Tetranychus urticae) on the primary leaves of cowpea plants (Vigna sinesis Savi species) by spraying.

Milbemycin alpha17 and related compounds synthesized from milbemycin A4: synthetic procedure and acaricidal activities.

Milbemycin alpha17, a 14-demethyl congener of milbemycin A4, has been reported as a natural product. In this paper, we report the successful development of a chemical derivation method to synthesize milbemycin alpha17 from milbemycin A4, as well as our use of a similar method to prepare 24-demethylmilbemycin A4 from the same precursor. The acaricidal activities of these compounds were assessed against the organophosphorus-sensitive two-spotted spider mites (Tetranychus urticae) on the primary leaves of cowpea plants (Vigna sinesis Savi species) by spraying.

Synthesis of 27-oxo, 27-hydroxymilbemycins A3 and A4 and novel 27-alkoxymilbemycins A3 and A4 from milbemycins A3 and A4 and their acaricidal activities.

27-Oxomilbemycins A3 and A4 and 27-hydroxymilbemycins A3 and A4 were identified as metabolites in soil metabolism studies of milbemycins A3 and A4. Chemical derivation methods were developed to synthesize 27-oxomilbemycins A3 and A4 and 27-hydroxymilbemycins A3 and A4 from milbemycins A3 and A4. In addition, 27-alkoxymilbemycin derivatives were also synthesized from the same precursors.

Synthesis of milbemycins alpha9, alpha10, alpha11, alpha12, alpha14, alpha15, alpha20, alpha21, alpha22, alpha23, alpha26, alpha27, delta(2,3),delta(4,26)-milbemycins A3, A4 from milbemycins A3, A4, and their acaricidal activities.

Chemical derivation methods to prepare 26-acyloxy and 26-hydroxymilbemycins, which had been reported as natural products, milbemycins alpha9, alpha10, alpha11, alpha12, alpha14, alpha15, alpha20, alpha21, alpha22, alpha23, alpha26, alpha27 from milbemycins A3, A4 were reported. Delta(2,3),delta(4,26)-milbemycins A3, A4, which had also been reported as natural products, were further prepared from milbemycins A3, A4. Their acaricidal activities were also assessed against the organophosphorus-sensitive two-spotted spider mite (Tetranychus urticae) on primary leaves of cowpea plants (Vigna sinesis Savi species) by spraying.

Synthesis and insecticidal activity of novel dihydropyrrole derivatives with N-sulfanyl, sulfinyl, and sulfonyl moieties.

This paper reports the synthesis and insecticidal activity of a new type of dihydropyrrole derivatives with sulfur moieties such as sulfanyl, sulfinyl, and sulfonyl groups at the 1-position. These derivatives exhibited high insecticidal potency against Nilaparvata lugens and Nephotettix cincticeps. Investigation of the structure-activity relationships revealed that the alkoxycarbonyloxy groups at the 4-position tended to increase the systemic insecticidal activity.

Synthesis and insecticidal activity of novel N-oxydihydropyrroles: 4-hydroxy-3-mesityl-1-methoxymethoxy derivatives with various substituents at the 5-position.

This paper reports the synthesis and insecticidal activity of a series of novel 4-hydroxy-3-mesityl-1-methoxymethoxy-1,5-dihydro-2H-pyrrol-2-one derivatives, in which the substituents at the 5-position were varied with a number of alkyl and spirocycloalkyl groups. Investigation of the structure-activity relationships revealed that small alkyl and spirocyclohexyl groups had a favorable effect on the insecticidal activity of these agents against Myzus persicae.

Synthesis and insecticidal activity of N-oxydihydropyrroles: 4-hydroxy-3-mesityl-5,5-dimethyl derivatives with various substituents at the 1-position.

A new series of N-oxydihydropyrrole derivatives was synthesized and evaluated for insecticidal activity against Nilaparvata lugens and Myzus persicae. Various substituents were introduced to the 1-position of the dihydropyrrole ring, and the derivatives obtained exhibited systemic and/or contact insecticidal activity. The structure-activity relationship revealed that small alkyoxy and alkoxyalkoxy groups were more favorable than alkylcarbonyloxy, alkoxycarbonyloxy, or sulfonyloxy groups as substituents at the 1-position.

Synthesis of milbemycins beta9 and beta10 from milbemycins A3 and A4 and their biological activities.

Chemical derivation methods were used to prepare milbemycins beta9 and beta10 from milbemycins A3 and A4. Their acaricidal activities were also assessed against the organophosphorus-sensitive two-spotted spider mite (Tetranychus urticae) on primary leaves of cowpea plants (Vigna sinesis Savi species) by spraying.