DEVELOPMENTS IN THE CHEMISTRY OF IONONES 453 (96) (97) (98) (99) (100) (101) (102) (103) (104) (105) (100) (107) (10S) (109) (110) (111) (112) (113) (114) (115) (116) (117) (118) (119) (120) (121) (122) Naves, Y. R. and Ardizio, P. Sur la production de la [t-ionone par la cyclisation des pseudo ionones au moyen d'acide sulfurique. Bull. Soc. Chirn. France, 661 (1954). French Pat. 1 410 645. Proc4dd de fabrication de [t-ionone. Kergomard, A. Sur l'dquilibre d'isomdrisation des ionones. Bull. Soc. Chirn. France, 1648 (1962). Semenovski, A. V., Smit, V. A. and Kucherov, A. V. Mechanism of cyclization of pseudoionone. Proc. Atari. Sci. U.S.S.R. Chern. Sect. English Transl. 132 687 (1960). Smit, V. A. and Kucherov, ,V. G. Cyclization reactions of isoprenoid compounds. Usp. Khim. 28 272 (1959). Smit, V. A., Semenovski, A. V., Medveda, V. M. and Kucherov, V. F. Character of cyclization of pseudoionone. Preparation ooe a-ionone Proc. Acad. Sci. U.S.S.R. Chern. Sect. English Transl. 124 141 (1959). de Boer, Th. J., Van't Itoff, M. A. and Veenland, ]. U. Cyclization of pseudoionone with deuterated sulphuric acid. Rec. Trav. Chirn. Pays-Bas, 83 689 (1964). Van't Hoff, It. A., Veenland, J. U. and de Boer, Th. J. On the mechanism of the cycliza- tion of pseudoionone with deuterated sulphuric acid. Tetrahedron 23 3757 (1967). Mursakuler, I. G., Semenovski, A. V., Smit, W. A. and Kucherov, V. F. Cyclization of terpenoid compounds--Stereochemistry of the addition to the terminal (2,3) double bond. Tetrahedron 23 1629 (1967). Ohloff, G. and Schade, G. Darstellung yon y-Jonon aus all-trans-Pseudo Jonon. Z. Angew. Chem., 76 944 (1962). Process for the preparation of compounds of the ionone series. Brit. Pat. 989 045. Ohioif, G., Mignat, S. l•lber Verbindung der ¾-Jonon Reihe. Ann. Chern., 652 118 (1962) Des combinaisons de la s4rie ¾-ionone. Dragoco Rept., 267 (1962). U.S. Pat. 3 238 260, Brit. Pat. 935 412. Production of ionone compounds. Royals, E. E. Cyclization of pseudoionone by acidic reagents. Ind. Eng. Chern., 38 546 (1946). Naves, Y. R., Wahl, R., Ardizio, P. and Favre, CI. Sur les r4actifs, 1es mdcanismes et les produits des cyclisations des pseudoionones. Bull. Soc. Chirn. France, 873 (1953). Naves, Y. R. Sur les r4actifs et les produits de cyclisation des pseudoionones. Cornpt. Rend. 236 1573 (1953). Naves, Y. R. and Ardizio, P. Sur un mode de cyclisation in4dit des pseudoionones et des pseudoirones. Bull. Soc. Chim. France, 494 (1953). Bogerr, ,hi. T. and Fourman, V. G. The catalytic dehydration of ionone and the con- stitution of ionene. ]. Am. Chern. Soc. 55 4670 (1933). Kruk, G., de Boer, Th. J., Haring, H. G., Ter-Iteide, R. and Boelens, It. By-products in the cyclization of pseudoionone to •-ionone. Structural determination of two new ionone isomers. Rec. Tray. Chirn. Pays-Bas, 87 641 (1969). Naves, Y. R. and Bachmann, P. Isolement d'un isom•re tricyclique des ionones. Helv. Chirn. Acta 27 645 (1944). Biichi, G., Koller, E. and Percy, C. W. Bicyclionones and tricycloionones. J. Am. Chem. Soc. 86 5646 (1964). Vogt, H. R. Ncue Bespiele saiirekatalysierter Ringschliisse bei den Monoterpenen, besonders nach dem Allo-cyclogeranyltyp. Thesis, Eidg. Techn. I{ochsch. Ziirich (1954). Naves, Y. R. and Odermatt, A. Applications de la chromatographie de partition vapeurs-liquide • l'analyse de m41anges de citrals ou de certains de leurs d4riv4s eux-mgmes isom•res. Bull. Soc. Chirn. France, 377 (1958). Naves, Y. R., Wahl, R., Ardizio, P. and Favre, C1. Sur les r•actifs, les m4canismcs et les produits de cyclisation des pseudoionones. Bull. Soc. Chirn. France, 881 890 (1953). U.S. Pat. 3 217 718. Tobacco. French Pat. I 456 296. Nouvelle synth•se de la d4hydro-ionone. Naves, Y. R. and Ardizio, P. Obtention de d4riv4s de l'hexahydro-chrom•ne & parfir d'ct, [t-dihydro-pseudoionones. Bull. Soc. Chirn. France, 1189 (1950).

454 (123) (124) (125) (126) (127) (128) (129) (130) (131) (132) (laa) (134) (135) (136) JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Kriner, M. Z., Smit, V. A. and Semenovski, A. V. Cyclization of isoprenoids compounds. Cyclization of geranylacetone under the action of deutero-sulphuric acid. Izv. Akad. Nauk. S.S.S.R., Set. Khim., 7 1573 (1968). Stair, V. A., Semenovski, A. V. and I(ucherov, V. F. Cyclization of isoprenoid com- pounds. Zone temperature cyclization of dihydro-a-, dihydro-•-and dihydro-¾-ionones Izv. Akad. Na•k. S.S.S.R., Set. Khim., 1601 (1963). Stoll, 3/[. and Hinder, 3/[. Cyclisation de la dihydro-¾-ionone. Helv. Chim. Acta, 38 15oa (1955). Stoll, M., Seidel, C. F., Willhalm, B. and Hinder, M. Sur la constitution de l'ambrinol (A 4-, A 9- et A 5, 10- trim4thyl-1, 1,5- hydroxy-6-octal•ne). Helv. Chim. Acta, 39 183 (1956). Stoll, M., Willhalm, B. and Bfichi, G. SynthSse du trim4thyl-l,l,5- m•thyl•ne-9- bicyclo-[3.3.1]-nonanol-5. Helv. Chim. Acta, 38 1573 (1955). U.S. Pat. 3 144 465. Interne Ketals from dihydro-7-Jonone, dihydro-¾-Irone and 5,5,9- trimethyl-2-methylene- 1-(3 '-oxo-bu•yl- 1 ')-decahydronaphthalenc. U.S. Pat. 3 217 717. Tobacco. Stoll, M. and Bolle, R. Synthbse d'4poxydes aromatiques. II. Epoxy-3,2(3)-t4tra- hydroionane. Helv. Chim. Acta, 33 900 (1950). Brit. Pat. 1 016 090 An improved tobacco. Products comprising the improved tobacco and process for improving tobacco. U.S. Pat. 3 217 716. Tobacco composition. Isler, O. Vitamina A e carotenoidi. ½him. Ind. Milan, 49 1317 (1967). Weedon, B.C. L. in Godwin, T. W. (Ed.). Chemistry and biochemistry of plant pigments 75 (1965) (Academic Press, London and New York). Saucy, G., Marbet, R., Lindlar, H. and Islet, O. •ber eine neue Synthese yon Citral und verwandten Verbindungen. Eine neue Synthese yon Pseudoionone and analogen Verbindungen. Helv. Chim. Acta 42 1945 (1959) Marbet, R. and Saucy, G. Chimia. 14 362 (1960). Kimel, W., Surmatis, J. D., Weber, J., Chase, G. O., Sax, N. W. and Ofner, A. Syn- theses of pseudoionone homologs and related compounds. J. org. ½hem. • 1611 (1957). DISCUSSION M•. W. R. LITTLE•OHN: Would you like •o commen• on the difference in odour of the ionones from various sources and various processes? THe L•CTU•E•: For many years the traditional raw materials for ionone pro- duc•ion have been the various lemongrass oils, supplemented in limited amounts by alternative citral-containing oils such as Litsea cithara Blume (or Litsea c•b•ba Per- soon) from the Far Eas•, B•ckho•si• cit•odo• and other Myrtaceae oils of genus Le•tos•e•m•m. Moreover, linalol from coriander oil has been used in the Soviet Union as a source of citral, but this is related •o the particular political conditions and is not a consideration of our Western countries. During recent years use has been made of citrals based on turpentine, produced either by oxidation of geraniol and nero1 from •-pinene or by pyrolysis of isopiperi- tenols from aopinene. More recently, advantage has been taken of the acetylenic synthesis, leading to dehydrolinalol from which ci•rals are obtained by the methods of Saucy and Marbet (135) the latter are tending to replace the direct production of pseudo-ionones from dehydrolinalol by the reaction of Kimel el al (136).