SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF AZOLO(2,3-B)-8-ARYLPYRAZOLO(4,3-C)PYRIMIDIN-5-ONES

Aryl-5-allylthioureidopyrazol-4-carboxylates (2a-c) were cyclised with sodium ethoxide in refluxing ethanol to the corresponding 1-aryl-5-al lylpyrazolo (3,4-d) pyrimidin-4-oxo-6-thiones (3a-c). Compounds 3a-c, were converted to 1-aryl-5-(1, omopropyl)pyrazolo(3,4-d)pyrimidin-4-ox o-6-thiones (4a-c), by using bromine in acetic acid. Cyclisation of 4a -c in anhydrous potassium carbonate and acetone gave bromomethylthiazo lido(2,3-b)-8-arylpyrazolo(4,3-e) pyrimidin-5-ones (5a-c), which on de hydrobromination yielded compounds 6a-c. 6a-c, on stirring with 20% H2 SO4 furnished 5H-2-methylthiazolo-(2,3-b)-8-arylpyrazolo (4,3-e) pyrim idin-5-ones (12a-c). 6a-c on bromination with bromine in acetic acid, in presence of pyridine yielded 5H-2-bromomethylthiazolo(2,3-b)-8-aryl pyrazolo (4,3-e) pyrimidin-5-ones (7a-c). Condensation of various seco ndary amines with 8a-c gave 5H-2-substituted aminomethylthiazolo-(2,3- b)-8-arylpyrazolo(4,3-e)- pyrimidin-5-ones (8a-c-11a-c). The character isation of the products has been done on the basis of elemental analys is, IR and H-1 NMR spectral data. All the newly synthesised compounds have been screened for antimicrobial activity against S. aureus, E. co li and C. albicans. Compounds 10a and 12a displayed significant antiba cterial and antifungal activities.