PURPOSE: To provide a new selective adenosine receptor agent composed of a xanthine derivative, which acts selectively as an adenosine receptor, is effectively used as a cardiotonic, a vasodilator, or the like, and acts with the minimum influence to the others.

CONSTITUTION: This compound is represented by formula I [R1 and R2 are each 1-4C alkyl, 2-4C alkenyl; Z is formula II, formula III (R3 is ethoro, fluoro or the like; (m) is 0-4; (n) is 1-4; X is H, OH)] including (R) and (S) enathiomers and racemic mixture, or salts thereof, e.g. 3,7-dihydro-8-[(1R)-methyl-2- phenylethyl]-1,3-dipropyl-1H-purine, 2, 60-dione. A compound of formula V which is prepared by successively conversion into nitroso compound and reduction of a compound of formula IV, is treated with isobutyl chloroformic acid and N-methylmorpholine, and is reacted with a compound of formula VI, then the product is further treated with tetrafluoro boric acid triethyl oxonium, and the resulting compound of formula VII is heated under reflux in benzene, to prepare the objective compound.