1,2,3-TRIAZOLE[4,5-D]PYRIDAZINES .3. SYNTHESIS OF NEW 4-AMINO DERIVATIVES AND THEIR AFFINITY TOWARD ADENOSINE RECEPTORS

This paper describes the preparation and adenosine receptor binding of new 1-benzyl-4-aminosubstituted-1,2,3-triazole[4,5- d]pyridazines and of other 4-aminoderivatives bearing in the 1 position other neutral substituents. The synthetic procedures consist of nucleophilic displacement reactions from the 4-chloro derivative (procedure 1), of displacement of O-sililated intermediates (procedure 2) and of the use of phosphorus pentoxide-triethylamine hydrochloride reagent (procedure 3). The A1 adenosine receptor affinity is confirmed for the 1-benzyl substituted compounds bearing in the 4 position an arylamino or cycloalkylamino group. In addition, the compound obtained by reaction with racemic alpha-methylbenzylamine shows an interesting A1 activity, unlike the 4-benzylamino derivative.