Fremgangsmåde til fremstilling af med avermectiner og milbemyciner beslægtede forbindelser

摘要

Antiparasitic compounds of formula (I): The broken line at the 22-23 position representing an optional double bond and either R<1> is H or OH and the double bond is absent or the double bond is present and R<1> is absent; R<2> is optionally substituted phenyl, or a group of formula (II): wherein X is 0, S or -CH2-, abc and d are 0-2 and a+b+c+d is H or Me R<4> is H, OH or 4<1>-(alpha-L-oleandrosyl)-alpha-L-oleandrosyloxy. The compounds are prepared by fermentation of Streptomyces avermitilis in the presence of an N-alkanoyl cysteamine thioester containing R<2>.