Isoln from Papaver armeniacum (L.) DC., Papaveraceae: Konowalowa et al., Ber. 68, 2161 (1935); from Euonymus europaea L., Celastraceae: Bishay et al., J. Pharm. Pharmacol. 23 (Suppl), 233S (1971); from Rhamnus frangula L., Rhamnaceae: Pailer, Haslinger, Monatsh. Chem. 103, 1399 (1972). Structure: eidem, J. Gen. Chem. USSR 10, 641 (1940). Synthesis: Marion et al., J. Org. Chem. 15, 216 (1950); Gibson et al., J. Heterocycl. Chem. 3, 99 (1966). Resolution: Knabe, Horn, Arch. Pharm. 300, 547 (1967); Farber, Giacomazi, Chem. Ind. (London) 1968 (2), 57.