Total synthesis method for theacrine

The invention relates to a total synthesis method for theacrine. The total synthesis method comprises the following steps: 6-amino-1,3-dimethyluracil is taken as a raw material and subjected to a nitrosation reaction, and an intermediate 6-amino-1,3-dimethyl-5-nitrosouracil is obtained; 6-amino-1,3-dimethyl-5-nitrosouracil is subjected to a reduction reaction, and an intermediate 1,3-dimethyl-5,6-diaminouracil is obtained; 1,3-dimethyl-5,6-diaminouracil is subjected to a cyclization reaction, and an intermediate 1,3-dimethyluric acid is obtained; 1,3-dimethyluric acid is reacted with a methylation reagent, and a product is obtained. Theacrine prepared with the method can be synthesized massively in industrial application without restriction of raw materials; the conversion rate and the yield are high, the synthesis is convenient, post-processing is simpler, and the method is suitable for large-scale production and can be widely popularized and applied; the method is not needed to be performed under a high pressure condition, has low requirement for equipment and reduces the incidence rate of danger; with adoption of recrystallization for preparing the target product, the product purity is high.