5,7-dichlorothiazolo[4,5-d]pyriMidine

A mixture of thiazolo[4,5-d]pyrimidine-5,7(4H,6H)-dione and phosphorous oxychloride is heated at reflux for 6 h. The reaction mixture is then cooled and poured onto ice/water with vigorous stirring, yielding a precipitate. The mixture was then filtered to yield 5,7-dichlorothiazolo[4,5-d]pyriMidine as a white solid.