From tubers of Corydalis cava (L.) Schweigg. & Korte (C. tuberosa DC., Fumariaceae): Gadamer, Arch. Pharm. 240, 19 (1902). Structure: Spth, Dobrowsky, Ber. 58, 1274 (1925). Synthesis: Spth, Holter, ibid. 59, 2800 (1926). Abs configuration: P. W. Jeffs, Experientia 21, 690 (1965); K. Iwasa et al., J. Org. Chem. 46, 4744 (1981).