Base-catalyzed, efficient synthesis of 5-substituted 3,6-dihydro-7H-1,2,3- triazolo[4,5-d]pyrimidin-7-ones

The carbodiimides 2, obtained from aza-Wittig reactions of iminophosphorane 1 with aromatic isocyanates, reacted with secondary amines or ROH to give 5-dialkylamino or 5-alkoxy 7H-1,2,3-triazolo[4,5-d]pyrimidin-7-ones 4 in the presence of a catalytic amount of EtONa in a mixed solvent (CH 2Cl2-ROH). Reactions of 2 with phenols in presence of catalytic potassium carbonate in MeCN gave 5-aryloxy-7H-1,2,3-triazolo[4,5-d] pyrimidin-7-ones 4 in satisfactory yields. © Georg Thieme Verlag Stuttgart.link_to_subscribed_fulltex