Synthesis method of desicitabine intermediate alpha-substituted deoxyribose

The invention provides a synthesis method of desicitabine intermediate alpha-substituted deoxyribose. The synthesis route is as follows: R refers to p-methyl benzoyl and X refers to chlorine atomin according to the formula 3 and the formula I. The synthesis method includes the following steps: 1) methylation reaction: a compound of formula 1 is reacted with methyl alcohol under acid catalysis to obtain a compound of the formula 2; 2) acylation reaction: the compound of the formula 2 is dissolved in an organic solvent and reacted with p-methyl benzoyl chloride under alkali catalysis to obtain acompound of the formula 3; 3) chlorination reaction: acetyl chloride is used to adjust the pH value of the acylation reaction solution at low temperature, the acylation reaction solution is filtered,is added with a low polar solvent A, and then is added with acetic acid solution of hydrogen chloride to react to obtain a compound of formula I. The synthesis method uses p-methyl benzoyl as a protective group in the process