Synthesis of 5-Keto-5-oxime Derivatives of Milbemycins and Their Activities against Microfilariae

Abstract

Starting from milbemycin D (1), milbemycin A4 (2) and milbemycin A3 (3), a series of 5-keto-5-oxime derivatives were synthesized by selective oximation at the α,β-conjugated carbonyl function of the 5-ketomilbemycins (4—6). The activities of the synthesized compounds were studied in dogs naturally infested with microfilariae of Dirofilaria immitis. The 5-keto-5-oximes of milbemycin D (7), A4 (8) and A3 (9) had quite high efficacy to control the microfilariae and more potency than their parents, while the 5-O-acyl oximes (11—15) also exhibited high activity. © 1991, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.