Tetrahydro-2H-pyran-2-one-d4 is the deuterium labeled Tetrahydro-2H-pyran-2-one. Tetrahydro-2H-pyran-2-one is an endogenous metabolite with antioxidant capacity. Tetrahydro-2H-pyran-2-one is the small active molecule and can be used as drug intermediate[1].