REGIOSELECTIVE SYNTHESIS OF SUBSTITUTED AND FUSED PYRAZOLO[1,5-A]PYRIMIDINES AS LEISHMANICIDES

Cyclocondensation of 3,5-diaminopyrazoles (1a-d) with ketene dithioace tals 2a,b and 5 separately in acidic and basic media yields 3,4 and 6a ,b. The latter on boiling with acetic anhydride affords the diacetyl d erivative 7a-c. Similar reaction of 1a-d with benzocyclic ketene dithi oacetals (8a,b) in acetic acid affords the angularly fused pyrazolo[1, 5-a]pyrimidines (9a-h). Refluxing of 9c with acetic anhydride affords the diacetyl derivative 11. Dethiomethylation of 9d,e,h with Raney nic kel in methanol yields 10d,e,h. Condensation-cyclization of 1a-d with ambident electrophiles, ethyl arylidenecyanoacetate and arylidenemalon onitrile in neutral medium separately provides 12 and 15a-c with the e xception of the aromatized products 17 and 14. Oxidation of 15 with DD Q affords 16 while the tetrahydro derivative 12 under similar reaction conditions remains unaffected. Attempts for condensation of 1 with ma lononitrile or benzyl malononitrile either in acidic or basic medium a lso remain unsuccessful. Some of the compounds have been screened for their leishmanicidal activity.