Carbon-13 and oxygen-17 nuclear magnetic resonance studies of organosulfur compounds: the four-membered ring sulfone effect

1980 ◽  
Vol 45 (23) ◽  
pp. 4807-4810 ◽  
Author(s):  
Eric Block ◽  
Ali A. Bazzi ◽  
Joseph B. Lambert ◽  
Steven M. Wharry ◽  
Kenneth K. Andersen ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Membered Ring ◽  
Organosulfur Compounds ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

Nuclear magnetic resonance studies. XL. Tricyclooctanone rearrangement, [3.2.1.0] → [3.3.0.0], via γ-enolization and a 2Hmr study of H/D exchange in tricyclic ketones

1984 ◽  
Vol 62 (7) ◽  
pp. 1385-1391 ◽  
Author(s):  
A. K. Cheng ◽  
Ashim K. Ghosh ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Membered Ring ◽  
Deuterium Incorporation ◽  
Magnetic Resonance Studies ◽  
Endo Isomer ◽  
Exchange Processes ◽  
Initial Transformation ◽  
Nuclear Magnetic

The effect of strongly basic conditions (t-BuO−/t-BuOH/185 °C) on the exo and endo isomers of 7,7-dimethyltri-cyclo[3.2.1.02.4]octan-6-one has been examined. While the exo isomer is stable, the endo isomer readily rearranges to 4,4-dimethyltricyclo[3.3.0.02.8]octan-3-one (6) which subsequently undergoes reduction of the three-membered ring. The initial transformation is one of very few examples of γ-enolate rearrangement. Experiments in tert-buiyl alcohol-O-d1 were carried out to establish the several sites of deuterium incorporation in the initial ketones and in 6 using 2Hmr. These results reveal the stereochemistry of γ-enolate formation and cleavage as well as the stereoselectivities and relative rates of the exchange processes.

13C nuclear magnetic resonance studies. 85. 13C spectra of several ring-contracted and -expanded steroids

1979 ◽  
Vol 57 (13) ◽  
pp. 1550-1556 ◽  
Author(s):  
Vinod Dave ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Membered Ring ◽  
Magnetic Resonance Studies ◽  
Systematic Examination ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

The 13Cmr spectra of several cholestanes including 13 A-homo-B-nor derivatives, 11 A-homo derivatives, and 8 B-nor examples have been examined. In addition the 13C data for a few of the corresponding androstanes and 16 precursors in the cholestane series are reported. Examples in both the 5α- and 5β-cholestane families were included. These results represent the first systematic examination of the 13C spectra of A-homo-B-nor steroids and should be useful for the characterization of other members in each series. These data also permit some tentative conclusions regarding the favored conformation for the seven-membered ring in the A-homo derivatives.

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