A practical, robust and scalable synthesis of 6-bromo-4-chlorothieno[2,3-d]pyrimidine starting from cheap bulk chemicals has been developed. The method involves four synthetic steps: Gewald reaction, pyrimidone formation, bromination, and chlorination. The process relies on standard laboratory equipment, allowing to obtain the product in an overall yield of 49% without using chromatography for purification of the product and intermediates.

中文翻译：

---

6-Bromo-4-Chlorothieno [2,3-d]嘧啶的改良制备方法

从廉价的散装化学品开始，开发了一种实用，可靠且可扩展的6-溴-4-氯噻吩并[2,3-d]嘧啶的合成方法。该方法涉及四个合成步骤：Gewald反应，嘧啶酮形成，溴化和氯化。该方法依赖于标准实验室设备，无需使用色谱法纯化产物和中间体即可获得总产率为49％的产物。