1,2,3-TRIAZOLE[4,5-D]PYRIDAZINES .4. PREPARATION AND ADENOSINE RECEPTOR-BINDING OF NEW 4 AND OR 7 AMINODERIVATIVES/

This paper reports the continuation of the studies on the 4-aminosubst ituted 1,2,3-triazole[4,5-d]pyridazine derivatives which had shown bin ding affinity towards adenosine receptors. Biological results confirme d the greater activity of a benzyl substituent in the 1 position and t he receptorial stereoselectivity related to the higher and more s elec tive A(1) affinity of the 4-D(+)-alpha-methylbenzylamino enantiomer 1b . The 4-phenylhydrazino substituent has shown an interesting binding a ctivity about equipotent towards A(1) and A(2) receptorial sites. A su rprisingly elevated A(1) affinity (Ki = 7 nM), 440 fold higher than A( 2) affinity, is presented by compound 1d, bearing a m-toluidino substi tuent.