Preparation of 25,26,26,26,27,27,27-heptafluoro-15-ketosterols labeled at C-23 with deuterium or tritium
Su X., Siddiqui A., Swaminathan S., Wilson WK., Schroepfer GJ.
Side-chain fluorinated 15-ketosterols are potent regulators of sterol synthesis. For investigations of their metabolism, we have prepared 3β- hydroxy-25,26,26,26,27,27,27-heptafluoro-5α-cholest-8(14)-en-15-one and its 7α-methyl and 8(14)-saturated derivatives with one deuterium or tritium atom at C-23. The isotopic hydrogen was introduced by reduction of 23-iodo-15- ketosterols with tributyltin deuteride or tritide. Mass spectral analyses of the deuterated sterols showed incorporation of one deuterium in the side chain, and 2 H and 13 C NMR showed that deuterium was present only at C-23. The tritiated sterols had specific activities of 82-179 mCi/mmol and showed high radiochemical purities.