References
- Buchi , G. , Hofheinz , W. and Paukstelis , J. V. 1969 . J. Am. Chem. Soc. , 91 : 6473 cf., G. H. Posner and G. L. Loomis, Tetrahedron Lett., 4213 (1978)
- Yoshioka , H. , Mabry , T. J. and Timmernann , B. N. 1973 . Sesquiterpine Lactones , 39 – 58 . University of Tokyo Press . cf.
- Hartshorn , M. P. and Kirk , D. N. 1964 . Tetrahedron , 20 : 2943 cf., J. M. Coxon, M. P. Hartshorn, and D. N. Kirk, Tetrahedron, 20, 2531 (1964) for a steroidal example: I. Kitagawa, H. Takino, H. Shibuya, and I. Yosioka, Chem. Charm. Bull. (Toyko), 23, 2686 (1975) for a eudesmanolide rearrangement
- 1980 . Northwestern University . Details of these transformations may be found in the PhD thesis of J. A. Kerschen
- Gunstone , F. D. and Heggie , R. M. 1935 . J. Chem. Soc. , : 1285
- Hartshorn, Kirk, and Coxon (ref 3) report bands at 5.69 and 5.90 μm for a steroidal dione analog of 11. Their structural assignment of the deoxy analog of 9 (RO[dbnd]H) is based on a carbonyl band at 5.90 μm and a two-proton resonance at 2.42δ. We find that the bridged dione 12 shows infrared absorption at 5.73 and 5.88μm. The bridged ketone has a carbonyl peak at 5.89μm and a band at 1.65δ in the nmr spectrum