A’-3a-Hydroxy-12-ketocholenic acid

A -3a-Hydroxy-12-ketocholenic acid (VI) represents another important starting material for cortisone syntheses (Fig. 5), and two useful methods for its preparation are given in Fig. 1. The first method (Schwenk and Stahl, 1947 McKenzie et al., 1948) involves a preferential acylation at C-3 of desoxycholic acid (III), followed by chromium trioxide oxidation... 

As shown in Fig. 1, both cholic and desoxycholic acids are readily convertible to A -3a-hydroxy-12-ketocholenic acid. A number of very ingenious transformations of this acid (I) have been developed in Kendall s laboratory and have opened several useful routes to cortisone. 

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