From leaves of Chimonanthus fragrans Lindle, Calicanthaceae: Hodson et al., Proc. Chem. Soc. London 1961, 465. Structure: Clayton et al., Tetrahedron 18, 1495 (1962). Synthesis: Hendrickson et al., Proc. Chem. Soc. London 1962, 383; Scott et al., J. Am. Chem. Soc. 86, 302 (1964); Hall et al., Tetrahedron 23, 4131 (1967).