(13α,14α)-14,19-Dihydro-12,13-[methylenebis(oxy)]-20-norcrotalanan-11,15-dione is an intermediate in synthesizing Monocrotaline-d4 (M526002), a labelled Monocrotaline (M526000) which is a toxic pyrrolizidine alkaloid isolated from Crotalaria spp. It is used for inducing pulmonary diseases in rats.