Nine cytotoxic [5/7] and [6/6] benzannulated steroid spiroketals were synthesized by palladium catalyzed spiroketalization of 5α and 5β-alkynediols derived from testosterone, diosgenin and cholesterol. The regioselectivity of the spiroketalization reaction is decisively influenced by the α or β-orientation of the hydroxyl group at C-5. NMR and single crystal X-ray diffraction corroborated the structure of the obtained compounds. Compounds bearing a cholestane skeleton exhibited higher cytotoxicity against U251 and T47D cells, and the BrdU incorporation assay suggests that the synthesized spiroketals inhibit cell proliferation.

中文翻译：

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钯催化合成苯甲酰化类固醇螺缩酮。

通过钯催化衍生自睾丸激素，薯os皂苷元和胆固醇的5α和5β-炔二醇合成了九种具有细胞毒性的[5/7]和[6/6]苯并环类固醇螺环酮。螺酮缩合反应的区域选择性受到C-5处羟基的α或β取向的决定性影响。NMR和单晶X射线衍射证实了所获得化合物的结构。带有胆甾烷骨架的化合物对U251和T47D细胞表现出更高的细胞毒性，BrdU掺入法表明合成的螺酮可抑制细胞增殖。