Pyrazolo[1,5-a]pyrimidine derivatives

摘要

PCT No. PCT/JP96/00955 Sec. 371 Date Oct. 10, 1997 Sec. 102(e) Date Oct. 10, 1997 PCT Filed Apr. 5, 1996 PCT Pub. No. WO96/32394 PCT Pub. Date Oct. 17, 1996The invention provides pyrazolo[1,5-a]pyrimidine derivatives which are useful as potent analgesics and represented by the formula wherein R1 is lower alkenyl, hydroxy(lower)alkyl, (lower)alkylthio(lower)alkyl, (lower)alkanoyloxy(lower)alkyl, (lower)alkoxy(lower)alkyl, furyl or thienyl, R2 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, R3 is hydrogen or halogen, and A is a single bond or lower alkylene.