δ-Valerolactam-d4 is a labeled analog of δ-Valerolactam (V091440), which is a useful synthetic intermediate. It is an intermediate used to synthesize Cenicriviroc (C256550), an experimental drug candidate for the treatment of HIV infection. It is also a starting material for a new route to hexahydrojulolidines, using intramolecular 1,4-cycloaddition.