Acta. 28, 1684 (1945)), where an appropriately substituted enamine (IX): ##STR12## wherein Z is as defined in formula (II) and R7 is a methyl or ethyl group, is reacted with diethyl malonate to give a compound of formula (X): ##STR13## wherein Z is as defined in formula (II), followed by refluxing the compound of formula (X) with acid to give the corresponding ??-pyridone VII.