Adenosine receptor A1 agonists.

A compound of formula (I): ** (Formula) ** wherein R2 represents C1-C3 alkyl, halogen or hydrogen; R3 represents an alkyl group of straight or branched chain of 1 to 6 carbon atoms; R1 represents a group selected from: (1) - (alk) n (C3-C7), including bridged cycloalkyl, said cycloalkyl group optionally substituted with one or more substituents selected from OH, halogen and (C1-C3) wherein (alk) represents (C1-C3) n represents 0 or 1; (2) an aliphatic heterocyclic ring group 4 to 6 members, containing at least one heteroatom selected from O, N or S, optionally substituted with one or more substituents selected from the group consisting of alkyl (C1-C3), - CO2 (C1-C4), -CO- (C1-C3), -S (= O) n-alkyl (C1-C3), CONRaRb (wherein Ra and Rb independently represent H or C1-C3) and = O, and, when there is a sulfur atom in the heterocyclic ring, said sulfur atom is optionally substituted with (= O) n, wherein n is 1 or 2; (3) (C1-C12) straight or branched chain, optionally including one or more O, S (= O) n (where n is 0, 1 or 2) or N substituted in the chain alkyl, said alkyl optionally substituted with one or more of the following groups: phenyl, halogen, hydroxy or NRaRb wherein Ra and Rb both represent alkyl (C1-C3) or hydrogen; (4) a fused bicyclic aromatic ring: ** (Formula) ** where B represents a heterocyclic aromatic group of 5 or 6 members containing 1 or more O, N or S wherein the bicyclic ring is attached to the nitrogen atom of formula (I) via a ring atom a, and ring B is optionally substituted with -CO2- (C1-C3); (5) a phenyl group optionally substituted with one or more substituents selected from: -halogen, -SO3H, - (alk) nOH, - (alk) n-cyano, - (O) n-alkyl (C1-C6) (optionally substituted with one or more halogens), - (alk) n-nitro, - (O) m- (alk) n-CO2Rc, - (alk) n-CONRcRd, - (alk) n-COR c, - (alk) n -SORe, - (alk) n-SO2Re, - (alk) n-SO2RcRd, - (alk) n ORc, - (alk) n- (CO) m NHSO2Re-, - (alk) n-NHCORc, and - (alk) n-NRcRd, wherein m and n are 0 or 1 and alk represents a (C1-C6) alkylene group or a (C2-C6) alkenyl group; and (6) a phenyl group substituted with a heterocyclic aromatic group of 5 or 6 membered heterocyclic aromatic group being optionally said substituted by (C1-C3) or NRcRd; where Rc and Rd each independently can represent hydrogen or C1-C3 alkyl, or when part of a NRcRd, Rc and Rd group together with the nitrogen atom can form a heterocyclic ring of 5 or 6.