PYRAZOLO[1,5-a]PYRIMIDINE DERIVATIVES

摘要

The invention provides pyrazoloÄ1,5-aÜpyrimidine derivatives which are useful as potent analgesics and represented by the formula <CHEM> wherein R<1> is lower alkyl, lower alkenyl, hydroxy(lower)alkyl, (lower)alkylthio(lower)alkyl, (lower)alkanoyloxy(lower)alkyl, (lower)alkoxy(lower)alkyl, furyl or thienyl, R<2> is pyridyl, 1-oxide-pyridyl, lower alkyl-substituted pyrazinyl, lower alkyl-substituted pyrimidinyl, or phenyl which may have 1 to 3 substituents selected from the group consisting of lower alkyl, lower alkoxy and halogen, R<3> is hydrogen or halogen, and A is a single bond or lower alkylene; with the proviso that when R<1> is lower alkyl, R<2> is lower alkyl-substituted pyrazinyl or lower alkyl-substituted pyrimidinyl.