N-[(2R,3S)-2-(2,5-Difluorophenyl)tetrahydro-5-oxo-2H-pyran-3-yl]carbamic Acid 1,1-Dimethylethyl Ester is a useful synthetic intermediate in the synthesis of Omarigliptin (O633100); a potent and selective dipeptidyl peptidase 4 (DPP-4) inhibitor used for the treatment of type 2 diabetes.