References
- 1989 . Author to whom correspondence should be addressed; NIH-AREA Award recipient 1986–89; ACS-PRF-G Award recipient, 1987–89. Presented in part by PGH at the . Eighth Annual Ester Humphrey Symposium . October 7 1989 . Burlington, VT : University of Vermont . and at the Eastern New York Section of the ACS Undergraduate Chemistry Research Symposium, Skidmore College, April 22, 1989, Abstract A2.
- Hoffmann , H. M. R. , Eggert , U. , Gibbels , U. , Giesel , K. , Koch , O. , Lies , R. and Rabe , J. 1988 . Tetrahedron , 44 : 3899 Recent synthetic work includes the following: Zizaene, (b) Barker, A. J.; Pattenden, G. J. Chem. Soc., Perkin Trans. 1 1983, 1901. (c) Hoffmann, H. M. R.; Henning, R. Helv. Chim. Acta 1983, 66, 828. (d) Piers, E.; Banville, J.; Lau, C. K.; Nagakura, I. Can. J. Chem. 1982, 60, 2965. (e) Pramod, K.; Rao, G. S. R. S. J. Chem. Soc., Chem. Commun. 1982, 762. (f) Alexakis, A.; Chapdelaine, M. J.; Posner, G. H. Tetrahedron Lett. 1978, 19, 4209. Khusimone (g) Wu, Y.-J.; Burnell, D. J. Tetrahedron Lett. 1988, 29, 4369. (h) Sakurai, K.; Kitahara, T.; Mori, K. Tetrahedron 1988, 44, 6581. (i) Oppolzer, W.; Pitteloud, R.; Bernardinelli, G.; Baettig, K. Tetrahedron Lett. 1983, 24, 4975. (j) Oppolzer, W.; Pitteloud, R. J. Am. Chem. Soc. 1982, 104, 6478. (k) Liu, H. J.; Chan W. H. Can. J. Chem. 1982, 60, 1081. For an excellent survey of methanohydroazulene synthetic work from 1970 to 1979 confer: (I) Heathcock, C. H.; Graham, S. L.; Pirrung, M. C.; Plavac, F.; White, C. T., in: The Total Synthesis of Natural Products; ApSimon, J. (Ed.); New York: Wiley Interscience, 1983; Vol. 5, pp 473–483.
- Lipa , W. J. , Crawford , H. T. , Radlick , P. C. and Helmkamp , G. K. 1978 . J. Org. Chem. , 43 : 3813 Tricyclic ketal 1 is prepared from commercially available 2-indanone (Aldrich) via ketalization and Birch reduction in 78% overall yield, confer:, (b) Birch, A.J.; Fitton. P.; Smith, D. C. C.; Steere, D. E.; Stelfox, A. R. J. Chem. Soc. 1963, 2209.
- Giguere , R. J. , Lopez , B. O. , Namen , A. M. and Majetich , G. Abstracts of Papers. 194th National Meeting of the American Chemical Society . New Orleans, LA . Washington, DC : American Chemical Society . Our group has re-investigated this tandem ene/intramolecular Diels-Alder process first observed by Alder and Bong in 1952, confer:,; ORGN 114. (b) Reference 5.
- Giguere , R. J. , Namen , A. M. , Lopez , B. O. , Arepally , A. , Ramos , D. E. , Majettch , G. and Defauw . 1987 . J. Tetrahedron Lett. , 28 : 6553
- Excess diene is presumably required to suppress competing intermolecular Diels-Alder reaction of ene adduct and dimethylacetylene dicarboxylate as discussed in reference 5. A portion of diene (ca. 10–15 %) also aromatizes under these conditions.
- Heut , F. , Lechevallier , A. , Pellet , M. and Conia , J. M. 1978 . Synthesis , : 63 Alternatively, trifluoroacetic acid in ethanol (9h, RT) provides ketone 4, but in somewhat lower yield (63%). Standard deprotection reagents (e.g., 2N HCI in aqueous dioxane, RT) require long reaction times (>40 h) and result in product mixtures of ketone 4 and methanohydroazulene 3 in diminished yields
- Base catalyzed conditions (NaH) also induce fragmentation, presumably via a retro-Michael reaction, but the yield of 3 suffers and other unidentified products are formed.
- Guivisdalsky , P. N. and Bittman , R. 1989 . J. Am. Chem. Soc. , 111 : 3077 For recent ring-opening applications that employ boron trifluoroetherate in dichloromethane, see, Rigby, J. H., Senanayake, C. J. Org. Chem., 53, 440 (1988).
- Marchand , A. P. 1982 . “ Stereochemical Applications of NMR Studies in Rigid Bicyclic Systems ” . 116 – 120 . 140 – 141 . Deerfield Beach, FI : Verlag Chemie International . Confer:, Table 24., Capillary GLC analysis reveals less than 5% of an unidentified product (RT = 12.91 min), presumed to be the exo C-10 epimer of 3
- We thank Prof. Leo A. Paquette (Ohio State) for a helpful discussion on this point. .