(3aR-cis)-Hexahydro-4-(phenylmethyl)-2H-furo[3,2-b]pyrrol-2-one-d2is synthesized from pyroglutamic acid. Also, it is an intermediate used in the synthesis of Monocrotaline-d4 (M526002), which is labelled Monocrotaline (M526000) which is a toxic pyrrolizidine alkaloid isolated from Crotalaria spp. It is used for inducing pulmonary diseases in rats.