PREPARATION OF 25,26,26,26,27,27,27-HEPTAFLUORO-15-KETOSTEROLS LABELED AT C-23 WITH DEUTERIUM OR TRITIUM

Side-chain fluorinated 15-ketosterols are potent regulators of sterol synthesis. For investigations of their metabolism, we have prepared 3 beta-hydroxy-25,26,26,26,27,27,27-heptafluoro-5 alpha-cholest-8(14)-en -15-one and its 7 alpha-methyl and 8(14)-saturated derivatives with on e deuterium or tritium atom at C-23. The isotopic hydrogen was introdu ced by reduction of 23-iodo-15-ketosterols with tributyltin deuteride or tritide. Mass spectral analyses of the deuterated sterols showed in corporation of one deuterium in the side chain, and H-2 and C-13 NMR s howed that deuterium was present only at C-23. The tritiated sterols h ad specific activities of 82-179 mCi/mmol and showed high radiochemica l purities.