A New Synthesis of 2γH-Pyran-2-ones 2H-Pyran-2-ones (2-pyrones) are easily prepared in high yield by a two-step sequence consisting of esterification of 2-diethoxyphosphinylalkanoic acids with alkyl 1-hydroxymethylenealkyl ketones using dimethylformamide/oxalyl chloride (Method of Stadler) and cyclization of the resultant 3-oxo-1-alkenyl 2-diethoxyphosphinylalkanoates by the Wittig-Horner-Emmons reaction.