210 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (I) Reduction ./•',••(•2 )Pyrolysis Elemene Germecrone H 2 (H) © Selinane 7' -- Cadinene B -Cad/nene Germberene--D J Jhv o - Amorphene • - Bourbonene Figure 10. • -- Muurolene ¾- Muurolene the latter. The hydrocarbons a- and [3-elemene occur in sweet-flag oil (34) and gurjun balsam (35) respectively, but have found no specific use in perfumery so far. The alcohol elemol found in Java citronella oil and elemi oil has the configuration as indicated and affords a-elemene on dehydration (36). Elemol has a faint, sweet-woody odour with an almost floral undertone, and the essential oil fractions rich in this alcohol are used as fixatives, blenders or modifiers in soap perfumery. The total synthesis of elemol was accomplished by Corey and Broger (37). The eudesmane group is probably the largest of the sesquiterpene groups and can be considered to have been derived from farnesyl pyro- phosphate cyclization involving a germacrane skeleton as an intermediate. The hydrocarbons a- and [i-selinene are found in Bols de Rose and celery

SESQUITERPENE$ IN THE PERFUMERY INDUSTRY 211 •:-Elemene •-- E f emene S -- E lemene ••OH E I emol Figure 11. seed oil (38, 39), whereas the alcohol [Peudesmol occurs in eucalyptus oil (40). a-Selinene has a mild, sweet-woody, and slightly peppery odour, the [Pisomer has a similar but warmer and more herbaceous odour (13). Eudesmol which finds some use as a fixative offers a delicate, sweet-woody and warm odour. The corresponding acetate ester is also interesting for its linalyl acetate type odour combined with much better tenacity. Both a-- Selinene /3-Selinene /•- Eudesmol Figure 12. selinene and [Peudesmol have been synthesized by Marshall, Pike and Carroll (41). Cyperene and a-cyperone also offer interesting structural systems, the latter being the main constituent of the oil of Cyperus rotandus (42). Penfold, Robinson and Simonsen (44) speculated a 1,2-alkyl shift in eudesmanes to generate the commercially important group of compounds known as eremophilanes (44). Eremophilene is present in a number of essential oils and has been a subject of several publications and a recent review by Pinder (43). The ketone Eremophilone is a constituent of Eremo- phiIIa mitcheIIi (44). The most commercially important members of the group are valencene, nootkatene, and nootkatone. Valencene has been isolated from orange juice oil and orange peel oil (45), and its structure and absolute configuration has been related to nootkatene, a t-butyl chromate oxidation product of'