How is 2,4-Dichloro-5,7-dihydrothieno[3,4-d]pyrimidine (CAS: 74901-71-6) typically synthesized?

2,4-Dichloro-5,7-dihydrothieno[3,4-d]pyrimidine can be synthesized through the reaction of 2,4-dichloropyrimidine with thiophene. The synthesis involves heating the reactants in a suitable solvent under mild conditions, followed by work-up procedures such as extraction and recrystallization to obtain the desired product. The process typically yields a high purity product with good selectivity.