“…Parasorbic acid [(+)5-methylpentene-2-lactone] is present in rowan berries (Doebner, 1894; Kuhn and Jerchel, 1943;Diemair and Franzen, 1959), and massoia lactone [(-)5-pentyl-pentene-2-lactone] has been extracted from the bark of the New Guinea massoia tree, Cryptocaria massoia (Meyer, 1940). Recently, Winter et al (1962) reported the isolation of a levorotatory unsaturated lactone, 5-(penten-2 cis-yl)-pentanelactone, from jasmine oil. Dextrorotatory -y-lactones can be prepared from the antibiotics nemotin and odyssine Leeming, 1955, 1957;Bu'Lock et al, 1956) or from (+)4dodecen-8-yl)-butanelactone (Friinkel, 1939), but a limiting factor is that these natural compounds can only be isolated in minute quantities.…”