2-Amino-8-cyclopropyl-5-oxo-5,8-dihydro-pyrido[2,3-d]-pyrimidine-6-carboxylic acid compounds

Claim 1

A compound of the formula ##STR45## or a therapeutically useful acid-addition salt thereof, in which R 1 is alkyl having 1 to 12 carbon atoms, optionally substituted by alkoxy having 1 to 4 carbon atoms or dialkylamino having 1 to 3 carbon atoms per alkyl radical; or alkenyl having 2 to 12 carbon atoms, R 2 is hydrogen; alkyl having 1 to 12 carbon atoms or hydroxyalkyl having 1 to 12 carbon atoms; R 1 and R 2 taken together with the nitrogen atom on which they are substituents and, optionally, with a further hetero atom selected from oxygen, sulphur or NR 4 , form a 5- to 7-membered ring which is optionally substituted on a carbon atom by 1 to 4 C 1 -C 2 -alkyl groups, R 4 is hydrogen; C 1 to C 6 alkyl, optionally substituted by hydroxy, alkoxy, alkylmercapto or dialkylamino group with 1 to 3 carbon atoms per alkyl radical or alkoxycarbonyl with 1 to 4 carbon atoms in the alkoxy moiety; cycloalkyl with 3 to 7 carbon atoms; phenylalkyl which has up to 4 carbon atoms in the aliphatic part and is unsubstituted or substituted in the phenyl part by halogen, C 1 -C 3 -alkyl, C 1 -C 3 -alkoxy, C 1 -C 3 -alkylmercapto, phenoxy, phenylmercapto, trifluoromethyl, nitro, cyano or carboxylic acid ester with 1 to 4 carbon atoms in the alcohol part; phenyl or pyridyl, pyrimidyl, thiazolyl or benzthiazolyl or alkoxycarbonyl which has 1 to 4 carbon atoms in the alkoxy moiety; or alkanoyl with 1 to 6 carbon atoms; phenyl-carbonyl; or aminosulphonyl; and R 3 is hydrogen or alkyl having up to 3 carbon atoms.