摘要：

The chemical conversion of a ring C unsubstituted steroid ("diosgenin") to cortisone via intermediates of the desirable 5β ("normal") series is described. Δ7,9,(11)-22a,5β-Spirostadien-3α-ol acetate (I), obtainable from "diosgenin," has been oxidized by Fieser's sodium dichromate procedure to a mixture of Δ8-22a,5β-spirosten-3α-ol-7,11-dione acetate (II) and Δ9(11)-22a,5β-spirosten-3α-ol-7-one acetate (III). The former on zinc reduction yielded the saturated diketone IV, from which the 7-ketone function was removed by conversion to the ethylenethioketal V and nickel desulfurization. The resulting 22a,5β-spirostan-3α-ol-11-one acetate (VI) on side chain degradation furnished Δ16-pregnen-3α-ol-11,20-dione acetate (VII) and thence on hydrogenation pregnan-3α-ol-11,20-dione acetate (VIII). The latter substance had previously been transformed to cortisone by Gallagher and co-workers.

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