VERFAHREN ZUR HERSTELLUNG VON 9-AMINO-6,7-DIHYDRO-4H-PYRIDO (1,2-A) PYRIMIDIN-4-ON-DERIVATEN, DEREN PHYSIOLOGISCH VERTRAEGLICHEN SALZEN, HYDRATEN UND ISOMEREN

A process is disclosed for the preparation of compounds of the formula (I) wherein R1 and R2 are each hydrogen or lower alkyl; R3 is carboxy, lower alkoxycarbonyl, carbamoyl, carbamoyl substituted by one or two lower alkyl groups, or cyano; R4 is hydrogen, lower alkyl, phenyl, naphthyl, phenyl or naphthyl substituted by at least one fluoro, chloro, bromo, iodo, lower alkyl, lower alkoxy, hydroxy, carboxy, or phenyl, pyridyl or tetrazolyl; and R5 is hydrogen or lower alkyl; or a pharmaceutically acceptable salt, hydrate, stereoisomer, optically active isomer, geometric isomer, or tautomer thereof, which comprises the step of aminating a racemic or optically active compound of the formula (II) wherein X is halogen with a compound of the formula (III) or a pharmaceutically acceptable acid addition salt thereof. The compound of formula (II) possess antiallergic, especially antiasthma, activity.