Pyridazine derivatives. XIX: Functionalization studies at the 5 position in the 6-phenyl-3(2H)-pyridazinone system

A series of 6-phenyl-3(2H)-pyridazinones bearing different substitution at the 5 position of the pyridazinone ring were prepared in the search for new platelet aggregation inhibitors. The structure of the final compounds was determined on the basis of spectroscopics methods.