13C NMR Studies of some Bicyclo[2.2.2]Octanones.a Characterization of the Isomeric 1,5,5,8-Tetramethylbicyclo[2.2.2]Octan-2-Ones
The 13C nmr spectra of a series of sixteen bicyclo[2.2.2]octenones and octanones have been determined to examine the variation of 13C shieldings with methyl substitution. The well-defined effects arising from 1,4-nonbonded interactions are apparent and are useful for stereochemical assignments. Evidence is presented to show that closely neighboring ´ carbons experience deshielding effects, in sharp contrast to the influence of steric crowding on y carbons. The 13C shieldings observed for 1,5,8,8-tetramethylbicyclo[2.2.2]oct-5-en-2-one and the isomeric saturated bicyclooctanones obtained therefrom establish their structures.
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- 2.(a) J.B. Grutzner, M. Jautelat, J.B. Dence, R.A. Smith and J.D. Roberts. J. Am. Chem. Soc. 92, 7107 (1970).(b) E. Lippmaa, T. Pehk, J. Paasivirta, N. Belikova and A. Plate. Org. Mag. Res. 2, 581 (1970).Google Scholar
- 3.J.B. Stothers, C.T. Tan and K.C. Teo. Can. J. Chem. 00t 0000 (0000).Google Scholar
- 4.For general discussions see (a) G.C. Levy and G.L. Nelson. 13C Nuclear Magnetic Resonance for Organic Chemists. Wiley-Interscience. New York, 1972; (b) J.B. Stothers. Carbon-13 NMR Spectroscopy. Academic Press. New York, 1972; (c) N.K. Wilson and J.B. Stothers in Topics in Stereochemistry. Vol. 8. edited by E.L. Eliel and N.L. Allinger. Wiley-Interscience, New York. 1973. Chap. 1.Google Scholar
- 6.S.H. Grover, J.P. Guthrie, J.B. Stothers and C.T. Tan. J. Mag. Res. 00, 0000 (0000).Google Scholar