Estradiol dehydrogenation

Double dehydrogenation and even complete aiomatization of the A-ring of 34iydroxy or 3-keto steroids can also be etiected the latter is of special interest in the preparation of estrogens, for example the conversion of the diene (60) to the a-estradiol derivative (61 equation 19) by Proactinomyces glob-erulaP ... 

Similar dehydrogenations are often accomplished biochemically. On treatment with Corynebacterium simplex, 19-nortestosterone is transformed into estradiol [1056], Many adrenocortical hormones are converted... 

The transformation of estradiol-17/3 to estriol has been postulated to proceed by dehydrogenation of estradiol to yield the enolic form of estrone followed by hydration to estriol (Fig. 20). Another hypothesis is that estrone is first oxidized to 16-ketoestrone and thence reduced to 16-keto-estradiol-17/8 and estriol. There is no experimental evidence in favor of... 

An example of the use of the isomerization of double bonds for the directed formation of a center of asymmetry is the isomerization of the 3-oxo-A ( compound (276) into the 3-hydroxy-A compound (277) in Velluz s total synthesis of estradiol (Scheme 72). In this reaction, taking place under the influence of acids or dehydrogenation catalysts, the product formed (277) has the more stable Sa-configuration. 

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