Synthesis of pyridazinone pharmaceutical intermediates using diketene reactant

Abstract

Valuable pyridazinone intermediates to pharmaceutically useful compounds can be prepared in surprisingly high yields by the reaction of the corresponding monohydrazone with diketene, preferably in the presence of a basic catalyst. In an especially preferred embodiment, p,p'-dichlorobenzil monohydrazone and diketene are reacted in a xylene solvent in the presence of triethylamine to afford 4-acetyl-5,6-bis(p-chlorophenyl)-2H-pyridazin-3-one, which can then be reacted with ethylene carbonate in the presence of potassium carbonate to afford the antihypertensive agent, 4-acetyl-5,6-bis(p-chlorophenyl)-2-(2'-hydroxyethyl)-2H-pyridazine-3-one.

Dependencies are inferred from the claim text.