A member of the hasubanan alkaloids. First alkaloid known to possess the unique dibenz[d,f]azonine structure. Isoln from Stephania japonica, Miers, Menispermaceae: H. Kondo, T. Sanada, J. Pharm. Soc. Jpn. 541, 177 (1927), C.A. 21, 27004 (1927); H. Kondo, T. Watanabe, ibid. 58, 268 (1938), C.A. 32, 54035 (1938). Structure: K. Takeda, Bull. Agric. Chem. Soc. Jpn. 20, 165 (1956). Synthesis: idem, C.A. 60, 5570f (1964); B. Pecherer, A. Brossi, J. Org. Chem. 32, 1053 (1967); A. R. Battersby et al., J. Chem. Soc. Perkin Trans. 1 1981, 2002. Biosynthesis: eidem, ibid. 2010, 2016, 2030.