(4)-hydroxy-pyrazolo-(3,4-d)-pyrimidine prodn. - by reacting (4)-ethoxycarbonyl-(3)-amino-pyrazole with ortho:formates and then with ammonia generated in situ

摘要

Prepn. of 4-hydroxypyrazolo (3,4-d) pyrimidine (I) comprises reacting 4-ethoxycarbonyl-3-aminopyrazole (II) with orthoformates and then with NH3 at high temp., pref. 120-140 degrees C. The NH3 is now generated in finely-distributed form from components of the reaction mixt.; esp. by thermal decomposition of NH4 cpds. added to mixt. before or during the heating stage. (I) is an inhibitor for xanthine-oxidase. The method gives high yields (about 90%) of high purity product, and avoids the use of excess gaseous NH3. Esp. the NH4 salts are lower carboxylates; alternatively NH3 is generated by reacting formamide and acetic acid. Pref. enough of these components are present to provide a stoichiometric amt. of NH3.