Phosphodiesterase (type III) inhibitors having the formula: which are useful in stimulating cardiac activity and in treating congestive heart failure and bronchoconstriction, pharmaceutical compositions including these inhibitors, and methods of using these compounds to produce phosphodiesterase (type III) inhibition in mammals
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(2008/06/13)
6-(substituted phenyl)-5-methyl-4,5-dihydropyridazin-3(2H)-ones of medicinal interest. The synthesis of SK&F 94836 and SK&F 95654
Two synthetic routes to the dihydropyridazinone-cyanoguanidine 4 (SK&F 94836) are described, both proceeding via the anilino compound 6. An efficient synthesis of the dihydropyridazinone-pyridone 5 (SK&F 95654) is reported. This synthesis proceeds via the fluoro-keto-acid 24, with subsequent displacement of the fluoro substituent by 4-pyridone. The surprising effectiveness of water as a solvent in this reaction has been highlighted.