作者:Gerardo M. Ramos Tombo、Oreste Gmsalba、Hans-Peter Schär、Bruno Frei、Peter Maienfisch、Anthony C. O’Sullivan
DOI:10.1080/00021369.1989.10869540
日期:1989.6
The diastereoselective hydroxylation of milbemycin A4 (1) at the 13/f-position (-*2) was performed by cultures of Streptomyces violascens (ATCC 31560). 14,15-epoxymilbemycin A4 (3) was formed via a parallel reaction as a byproduct. The conversion and the product ratio, 2/3, were improved by the addition of organic solvents. The best results, i.e., 91 % conversion with 92 % 2 and 8 % 3, were obtained by adding 2.5% DMSO to the culture broth. Oxime 7 was also hydroxylated at the 13β-position by S. violascens under similar conditions. In the case of milbemycin A3 (9) and D (10), the main products after treatment with S. violascens were the corresponding 14,15-epoxides, 13 and 14, respectively.
米尔贝霉素 A4 (1) 在 13/f 位 (-*2) 的非对映选择性羟基化反应是由 Streptomyces violascens (ATCC 31560) 培养物进行的。14,15-epoxymilbemycin A4 (3) 作为副产品通过平行反应生成。通过添加有机溶剂,提高了转化率和产品比率(2/3)。在培养液中加入 2.5% 的二甲基亚砜(DMSO)可获得最佳结果,即 91% 的转化率,92% 的 2 和 8% 的 3。在类似条件下,肟 7 也被 S. violascens 在 13β 位羟化。至于米尔贝霉素 A3(9)和 D(10),经 violascens 菌处理后的主要产物分别是相应的 14,15-环氧化物 13 和 14。