Isoln from the mushroom Clitocybe nebularis (Batsch.) Quel., Agaricaceae: Ehrenberg et al., Sven. Kem. Tidskr. 58, 269 (1946); L"ofgren et al., Acta Chem. Scand. 8, 670 (1954); from a streptomycete: Isono, Suzuki, J. Antibiot. 13A, 270 (1960). In vitro toxicity towards sarcoma 180 cells, mouse embryonic fibroblasts and epithelial cells: J. J. Biescle et al., Cancer 8, 87 (1955). Synthesis: Brown, Weliky, J. Biol. Chem. 204, 1019 (1953); Fox et al., J. Am. Chem. Soc. 80, 1669 (1958); Hashizume, Iwamura, Tetrahedron Lett. 1966, 643; eidem, J. Org. Chem. 33, 1796 (1968). Crystal structure: T. Takeda, Acta Crystallogr. 30B, 825 (1974). Alternate syntheses: V. Nair, S. G. Richardson, Tetrahedron Lett. 1979, 1181; P. K. Gupta, D. S. Bhakuni, Indian J. Chem. 20B, 534 (1981). Toxicity studies: Truant, D'Amato, Fed. Proc. 14, 391 (1955).