The Wittig reaction between phosphonium salt 1 and the hydroxybutenolide 2 followed by deprotection, macrocyclisation, and reduction gives the 6-hydroxymilbemycin E 9 which by further cyclisation is converted into milbemycin G 11.
鏻盐 1 和羟基
丁烯内酯 2 发生维蒂希反应,然后进行脱保护、大环化和还原反应,得到 6-羟基米尔贝霉素 E 9,进一步环化后可转化为米尔贝霉素 G 11。