25-hydroxy-7-dehydrocholesterol synthetic method

The present invention relates to a 25-hydroxy-7-dehydrocholesterol synthetic method, a 25-hydroxy-7-keto-cholesterol derivative is used as a raw material for mechanical milling reaction in a ball mill pot under the effect of sulfonyl hydrazide and a base in the absence of an organic solvent, and then hydrolysis reaction is performed to obtain 25-hydroxy-7-dehydrocholesterol synthetic method. According to the method, in the absence of a solvent, mechanical milling reaction is performed, no dust is spilled over in the grinding process, reaction controllability is good, reaction efficiency is high, the solvent recovery operation in the post-processing process can be avoided, operation is simplified, environmental pollution is reduced, the reaction selectivity is good, yield is high, operation is simple, cost is low, post-treatment is simple, three-waste is less, product is easy to separate, purity is high, the yield is up to 89%, the melting process is short, and the product purity is high.