Found in the acorns of various spp of Quercus, Fagaceae: Prunier, Ann. Chim. Phys. 15, 1 (1878); from leaves of the European palm (Chaemerops humilis): Muller, J. Chem. Soc. 91, 1766 (1907). Configuration: Posternak, Helv. Chim. Acta 19, 1007 (1936). Synthesis: G. E. McCasland et al., J. Org. Chem. 33, 4220 (1968).