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, and2H and13C 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.