Synthesis of di- and tri-substituted adenosine derivatives and their affinities at human adenosine receptor subtypes.

The synthesis of 2-(hex-1-ynyl)adenosine derivatives substituted at the N-6 - and/or 5'-position was carried out on the basis that 2-(hex-1-ynyl)adenos ine-5'-N-ethyluronamide (HENECA, 2) showed good affinity and different degr ee of selectivity for rat adenosine receptors. All new compounds were teste d in radioligand binding and adenylyl cyclase assays with recently cloned h uman A(1), A(2A), A(2B), and A(3) adenosine receptors.