AN EFFICIENT SYNTHESIS OF 3-PHOSPHORYLATED 4(1H)-PYRIDONES AND 4-CHLOROPYRIDINES FROM BETA-ENAMINOPHOSPHONATES

An easy and efficient synthesis of 4(1H)-pyridones (1) substituted wit h a phosphate group in the 3-position is described. The key step is an addition of beta-enaminophosphonates (2) to acylketene (3) generated either from diketene (4) or from the ''diketene-acetone adduct'', 2,2, 6-trimethyl-4H-1,3-dioxin-4-one (5), Subsequent treatment of 4(1H)-pyr idones with phosphorus oxychloride in the presence of dimethylformamid e afforded the substituted 4-chloropyridine (6).