282 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (36) Cf. Porsch, F., Farnow, H. and Winklet, H. Preparation of (-)-cis-pulegol. Dragoco Rept. l0 263 (1963) [Chem. Abs. 00 8064f (1964)]. (37) Cocker, W., Pratt, A. C. and Shannon, P. V. R. The Chemistry of Terpenes. Part V. The Preparation of Some Stereoisomeric Caranamines and a Study of their Confor- mations. y. Chem. Soc. [C] 484 (1968). (38) Baeyer, A. Ortsbestimmungen in der Terpenreihe. Ber. 27 3485 (1894). (39) Kuczyfiski, H., Piatkowski, K., Hendrich, A. and Kubik, A. Zur Konformation der Caran-5-ole und Caryl-5-amine, Tetrahedron Letters 2371 (1967). (40) Rathke, M. W., Inoue, N., Varma, K. R. and Brown, H. C. A stereospecific synthesis of alicyclic and bicyclic amines via hydroboration. J. Am. Chem. Soc. 88 2870 (1966). (41) Barton, D. H. R. and Morgan, jun., L. R. Photochemical transformations. Part XII. The photolysis of azides. J. Chem. Soc. 622 (1962). (42) Cf. Franklin, N.C. and Feltkamp, H. Conformational analysis of cyclohexane derivatives by nuclear magnetic resonance spectroscopy. Angew. Chem. Intern. Ed. 4 774 (1965). (43) Karplus, M. Contact electron-spin coupling of nuclear magnetic moments. J. Chem. Phys. 30 11 (1959). (44) Williamson, K. L. and Johnson, W. S. The proton magnetic resonance spectra of some a-acetoxy ketones. J. Am. Chem. Soc. 88 4623 (1961). (45) See e.g. Bhacca, N. S. and Williams, D. H. Applications of N.M.R. spectroscopy in organic chemistry 49 (1964) (Holden-Day, San Francisco). (46) Eliel, E. L. Conformational analysis in mobile cyclohexane systems. Angew. Chem. Intern. Ed. 4 761 (1965). (47) Cocker, W., Hanna, D. P. and Shannon, P.V.R. The chemistry of terpenes. Part IX. Deamination of the caranamines. J. Chem. Soc. [C] 1302 (1969). (48) Cf. Kropp, P. J. Cyclopropyl participation in the Carane system. J..4 m. Chem. Soc. 88 4926 (1966). (49) Narayanan, C. R., Bhadane, N. R. and Sarma, M. R. The conformation of primary hydroxyl groups in terpenmds, Tetrahedron Letters 1561 (1968). Demarco, P. V., Farkas, E., Doddrell, D., Mylari, B. L. and Wenkert, E. Pyridine-induced solvent shifts in the nuclear magnetic resonance spectra of hydroxylic compounds. J. Am. Chem. Soc. 90 5480 (1968) (50) Kuczy•ski, 'H., Walkowicz, M., Walkowicz, C., Nowak, If. and Stemion, I. Z. Crystalline (-)-3,4-dibromocarane. Roczniki Chem. 38 1625 (1964) Chem. Abstrs 62 9176 (1965). (51) Serumlet, F. W. and Schiller, H. yon. Beitr•.ge zur Kenntnis des iitherischen Oles aus den Kienstubben und Wurzeln yon Pinus silvestris (Iiefernwurze161) und sein Vergleich mit Stamm- und Nade151en dieser Pinus-Art. Bet. 60 1591 (1927). (52) Simonsen, J. and Owen, J. The constituents of Indian turpentine from Pinus longifolia, Roxb. Part VI. The auto-oxidation of d- A 3-Carene. J. Chem. Soc. 3001 (1931). (53) Burns, W. D. P., Carson, M. S., Cocker, W. and Shannon, P. V. R. The Chemistry of Terpenes. Part VIII. Some volatile neutral products of the oxidation of (-{-)-Car-3-ene with permanganate. J. Chem. Soc. [C] 3073 (1968). (54) Carson, M. S., Cocker, W., Grayson, D. H. and Shannon, P. V. R. The chemistry of terpenes. Part X. Oxidation of (-{-)-Car-3-ene with chromium trioxide. f. Chem. Soc 2220 (1969). (55) Chien, C.-T., Yeh, C.-C. and Tai. -H. Hydroboration of functionally substituted olefins. I and II, Acta Chim. Sinica 81 370, 376 (1965) and refs. therein. Chem. Abstrs. 64 8022 (1966). (56) van Tamelen, E. E., McNary, J. and Lornitzo, F. A. Mechanism of the carvone hydro- bromide ß eucarvone transformation. f. Am. Chem. Soc. 79 1231 (1957). (57) Woodward, R. B. Structure and absorption spectra of a, •]-unsaturated ketones. Am. Chem. Soc. 63 1123 (1941). Scott, A. I. Interpretation of the Ultraviolet Spectra of Natural Products 58 125 (1964) (Pergamon, Oxford). (58) Corey, E. J. and Burke, J. H. Formation of Carene [Bicyclo (4.1.0)heptene] derivatives from eucarvone, f. Am. Chem. Soc. 78 174 (1956). Cf. Zabza, A. and Kuczynski. Stereo- chemistry of the Carane system. Roczniki Chem. 40 463 (1966). (59) Boyle, P. H., Cocker, W., Grayson, D. H. and Shannon, P. V. R. The Chemistry of Terpenes. Part XII. Oxidation of (-{-)-Car-3-ene with tert.-butyl chromate and photo- lysis of the major oxidation product, (-)-Car-3-en-5-one. J. Chem. Soc. [C]. In press. (60) Carson, M. S., Cocker, W., Evans, S. M. and Shannon, P. V. R. Photolysis of (-)-cis- caran-4-one. Tetrahedron Letters 6153 (1968). (61) Heckert, D.C. and Kropp, P. J. The photochemistry of •], ¾-cyclopropylketones (-)-c{s- and trans~4-Caranone. J. Am. Chem. Soc. 90 4911 (1968).

SOME INVESTIGATIONS OF THE CHEMISTRY OF CARENE 283 (62) Carson, M. S., Cocker, W., Evans, S. M. and Shannon, P. V. R. The Che•nistry of Ter- penes. Part XI. Volatile products of the photolysis of (+)-cis-Caran-5-one. J. Chem. Soc. [C] 1447 (1970). (63) Dauben, W. G., Schutte, L. and Wolfe, R. E. Solution photolysis of cis- and trans-2- Methylcyclopropyl methyl ketone. J. Org. Chem. i•4 1849 (1969). Kropp, P. J. in Chap- man, O. L. Organic Photochemistry ?? I (1967) (Arnold, London). DISCUSSION DR. E. T. THEIMER: You stated that there was convincing evidence that both 2- and $-carene had a "boat" configuration and therefore give exclusively cis-carane on hydrogenation. Have you investigated the behaviour of 2,10-carerie on hydro- genation? One might expect a more stretched out configuration leading to substantial amounts of trans-carane. THE LECTURER: Are you referring in particular to what we all call beta carene the car-l , 10erie? DR. E. T. THEIMER: Yes. THE LECTURER: We have hydrogenated car-l , 10-ene, and as you surmise, we get almost equal quantities of cis- and trans- cararies. The double bond is placed so that there is not much more hindrance to attack on the top side than the bottom side. We have also hydrogenated car-4-ene (formula 21). This is recent work which I was unable to include in the paper. Based upon the hydrogenation of car-2-ene, hydrogenation of car-4-ene across the 4,7- positions might be expected. In fact, during this hydrogenation the double bond migrates out of conjugation with the cyclopropane ring giving initially car-$-ene which is converted to car-2-ene and thence to 1,1,4- trimethylcycloheptane. Incidentally, the reduction of car-4-ene is much slower than that of either car-2- or car-S-erie. If the reaction is monitored, the initial formation of car-S-erie can be recognised, and this is converted to car-2-ene followed by its dis- appearance and the formation of 1,1,4-trimethylcycloheptane. DR. E. T. THEIMER: Does this take place independently of the catalyst used? THE LECTURER: Yes, under the same conditions of hydrogenation as described for the hydrogenation of car-$-ene. I have no doubt, however, that if we hydrogenated at 10.1 MN m-2 pressure of hydrogen, cis-carane would result. It is a question of the relative speeds of addition of hydrogen to the double bond and migration of the double bond. I believe that under pressure direct hydrogenation across the double bond would be faster than either double bond migration or 1,4- addition of hydrogen to give 1,1,5-trimethylcyclohept-2-ene. DR. E. T. THEruER: Did you use a palladium on carbon catalyst? \Ve know that it is an extremely rapid isomerisation catalyst for double bonds. In the case of B-pinene, you can go to a-pinene with that system in about 5 min at 160-170 ø. If, however, you were to use say, nickel or something that was not so good an iso- merising agent, I wonder whether it would be possible to get 1,4- addition of hydrogen to give 1,1,5-trimethylcyclohept-2-ene. THE LECTURER: I think that under such conditions 1,1,5-trimethylcyclohept-9.-ene would result. It is, however, strange that car-4-ene fails to undergo a similar reaction