From ylang-ylang oil: Heraut, Dimitrov, Chem. Listy 46, 432 (1952); from oil of birch buds: Holub et al., Collect. Czech. Chem. Commun. 24, 3730 (1959); from oil of Juniperus oxycedrus Linn., Cupressaceae: Motl et al., ibid. 25, 1656 (1960). Structure: Motl et al., Chem. Ind. (London) 1963, 1759; Hunter, Brogden, J. Org. Chem. 29, 982 (1964); Motl et al., Tetrahedron Lett. 1965, 451. Stereoisomer of copaene, q.v. Total synthesis of (±)-form: Heathcock et al., J. Am. Chem. Soc. 89, 4133 (1967); Corey, Watt, ibid. 95, 2303 (1973).