Dihydro-?4-?(3-?pyridinylcarbonyl)?-2(3H)?-?furanone-d2 is an intermediate in synthesizing 4-Hydroxy-1-(3-pyridyl)-1-butanone-4,4-d2 (H953001), a tobacco-specific nitrosamine adduct and metabolite of NNK, 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone.