Method for synthesizing avanafil impurities

The invention discloses a method for synthesizing avanafil impurities, which belongs to the field of drug synthesis and has the advantages of reasonable process design, strong operability and mild reaction conditions. The preparation method comprises the following steps: A. hydrolyzing 4-(3-chlorine-4-methoxy phenylamino)-5-ethoxy carbonyl-2-methylthio pyrimidine I serving as a raw material in the presence of alkali to obtain a compound II; B, condensing the compound II and 2-aminomethylpyrimidine hydrochloride III under an alkaline condition to obtain a compound IV; C, oxidizing the compound IV in the presence of an oxidant to obtain a compound V; and D, reacting the compound V under an alkaline condition to obtain the avanafil impurity VI. According to the avanafil impurity prepared by the method, the impurity spectrum of avanafil is perfected, an important basis is provided for quality research of avanafil, and the safety of avanafil is further improved through research and control of the impurity. 本发明公开了一