Study On The Method Of7-Dehydrocholestrol

An HPLC-UV method for the quantitative and qualitative determination of intermediates of VitaminD3has been studied. Chromatographic analysis was carried out on the direct phase (SiO2)and reverse phase(C18) columns, and separation Conditions for the two kinds of columns were optimized.The optimum separation Conditions for the direct phase columu:hexane:tetrahydrofuran(v:v/95:5), velocity of flow of the mobile phase(1mL/min),columu temperature(25℃).The optimum separation Conditions for the reverse phase columu:mechanol:acetonitrile (v:v/95:5), velocity of flow of the mobile phase(1mL/min), columu temperature(30℃).The two kinds of columus had their own merits and demerits,however their separation efficiency can meet the experimental criteria.The whole synthetical route was divided into four steps. In the first step reaction the cholesteryl acetate was synthesized by cholesterol and acetic anhydride in benzene.The optimum reactive conductions: cholestero15.000g,benzene20mL, Pyridine2mL, acetic anhydride2.44mL, p-toluenesulfnic acid0.050g,reactive time3h, reactive temperature80℃, conversion98.0%.In the second step reaction, the cholestery acetate was oxided by CrO3/t-BuOOH in CH2C12and the7-ketocholestery acetate was obtained. The optimum reactive conductions:cholesteryl acetate1.715g, CH2C1220mL,CrO30.010g, t-butylhydroperoxide2.44mL, reactive time72h, reactive temperature25℃,conversion63.5%.In the third step reaction,the Tosylhydrazones was synthesized by7-ketocholestery acetate and4-Methylbenzenesulfonyl hydrazide in ethanol, using p-toluenesulfnic acid as catalyst.The optimum reactive conductions:7-ketocholeseryl acetate0.174g,1.5eq4-Methylbenzenesulfonyl hydrazide, p-toluenesulfnic acid0.015g, ethanol30mL, reactive time24h,reactive temperature30℃,conversion95.5%.The last step named Banford-Steven reaction,eventually7-dehydrocholesterol was prepared by NaH and Tosylhydrazones in DMF The optimum reactive conductions:Tosylhydrazones0.179g, DMF30mL,6eq NaH, reactive time3h,reactive temperature150℃,conversion73.0%.The total conversion of the four-step reaction was about45.5%.Baced on the above optimum reactive conditions,the whole synthetical route wae amplified and the reactive conditions were optimized.the conversion in every step was97.0%-98.0%,41.0%,98.0%,43.0%,the total conversion was16.9%.