Intermediate in morphine synthesis; naturally occurring in (+)-form. Isolated from various species of Croton and Papaver: Barton et al., J. Chem. Soc. 1965, 2423; Pfeifer, Kühn, Pharmazie 23, 267 (1968). Structure and identity with floripavine: Mndzhoyan et al., C.A. 68, 114787w (1968). Synthesis: T. Kametani et al., J. Chem. Soc. C 1969, 2030; G. Horvath, S. Makleit, Acta Chim. Acad. Sci. Hung. 106, 37 (1981); of racemate: T. Kametani et al., J. Chem. Soc. Perkin Trans. 1 1972, 1435; C. Szántay et al., J. Org. Chem. 47, 594 (1982); of racemate and (-)-form: W. Ludwig, H. J. Schafer, Angew. Chem. Int. Ed. 25, 1025 (1986). Review: Stuart, Chem. Rev. 1971, 47.