SYNTHESIS AND MOLECULAR-STRUCTURE OF 6-ARYL-3-ETHOXYCARBONYL-4-HYDROXYPYRIDAZINES

Ethyl Z-5-aryl-2-diazo-5-hydroxy-3-oxopent-4-enoates interact with tri phenylphosphine to give 6-aryl-3-ethoxycarbonyl-4-hydroxypyridazines ( Ar = Ph, 4-MeC6H4, 4-ClC6H4). Quantum-chemical calculations (MNDO) wer e performed to estimate the tautomeric equilibrium in the latter using a 6-phenyl-substituted derivative as an example. Acetylation of the 4 -hydroxypyridazines led to 4-acetoxy-6-aryl-3-ethoxycarbonylpyridazine s. The structure of the latter was confirmed by an X-ray diffraction a nalysis of 4-acetoxy-3-ethoxycarbonyl-6-(p-tolyl)pyridazine.