3-Methyl-2-oxo-valeric-d9 Acid Ethyl Ester is an intermediate in the synthesis of 3-Methyl-2-oxovaleric Acid-d8 Sodium Salt (Major) (M326423), which is the labelled 3-Methyl-2-oxovaleric Acid, an α-ketomonocarboxylic acid that triggers insulin release by acting upon receptor sites which differ from those occupied by amino acids. 4-Methyl-2-oxovaleric Acid is an analogue of Isoleucine.