The factors which determine the specific positions at which steroids are hydroxylated by micro-organisms are being investigated, using mono-ketones or keto-alcohols of the androstane series as substrates and infra-red and n.m.r. spectroscopy to determine the structures of the products. Whereas the major product of the hydroxylation of 5o-androstan-3-one by cultures of Calonectria decora is 123,l5x-dihydroxy-5eL-androstan-3-one, by contrast, with the 17ketone as substrate, I I,6oc-dihydroxylation occurs. The hydroxyl groups introduced are on centres about 4 A apart and at distances from the carbonyl 'directing' group which are approximately comparable. With a range of other substrates and with several other organisms results of a similar nature are obtained, revealing the dependence of the substitution pattern on the position of the oxygen function(s) of the substrate. The regio-specific reactions of organic compounds are usually associated with the presence of functional groups. Substitution is facilitated by bond polarization, i.e. the presence of a good leaving group or of adjacent activat.ion. Substitution at remote sites can only be achieved by transmitting these effects by appropriate means. The organic chemist has become very ingenious at this, constructing scaffolding enabling him to activate remote positions. In recent years, however, we have seen developments in what is now referred to as 'the functionalization of unactivated carbon'. The first instance was the quite unexpected transannular substitutions1 observed independently in medium-sized rings by Cope and Prelog. The Barton reaction2, initially demonstrated with steroidal 20-nitrites, is both of great practical value and of theoretical interest. It made aldosterone (II) available in just three steps from the relatively accessible corticosterone (I) and, in my view,

中文翻译：

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类固醇和相关化合物的微生物羟基化

正在研究决定类固醇被微生物羟基化的特定位置的因素，使用雄烷系列的单酮或酮醇作为底物，并使用红外和核磁共振光谱来确定产品的结构。而 5o-androstan-3-one 羟基化的主要产物是 123,15x-dihydroxy-5eL-androstan-3-one，相比之下，以 17ketone 作为底物，发生 II,6oc-dihydroxylation . 引入的羟基在中心相距约 4 A 并且与羰基“导向”基团的距离大致相当。使用一系列其他底物和其他几种类似性质的生物获得了结果，揭示了取代模式对底物氧功能位置的依赖性。有机化合物的区域特异性反应通常与官能团的存在有关。键极化促进了取代，即存在良好的离去基团或相邻的活化。远程站点的替代只能通过适当的方式传输这些影响来实现。有机化学家在这方面变得非常巧妙，建造了脚手架，使他能够激活远程位置。然而，近年来，我们已经看到了现在被称为“未活性炭功能化”的发展。第一个实例是 Cope 和 Prelog 在中等大小的环中独立观察到的相当出乎意料的跨环取代。Barton 反应 2 最初用甾体 20-亚硝酸盐证明，具有重要的实用价值和理论意义。它使醛固酮 (II) 从相对容易获得的皮质酮 (I) 只需三个步骤即可获得，在我看来，