ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Two isomeric 2,4,6,8-tetrabromo-cyclooctane-1,5-diones (8a and 8b) are formed in the tetrabromination of cyclooctane-1,5-dione (7). Treatment of a mixture of 8a and 8b with triethylamine gives rise to anti- 1,3-dibromo-bishomoquinone (9), which is reduced with zinc to anti-bishomoquinone (4) in a 65% overall yield. Either 8a or 8b, when heated with copper powder in a high vacuum, affords 1-bromo(11) and 1,3-dibromo-anti-bishomoquinone (9), anti-bishomoquinone (4) itself as well as its sys-isomer (5). The anti-configuration was assigned to 4 on the basis of its reduction to two diols, one of which showed NMR. coupling of its two isochronic carbinol protons with one cis-vicinal proton and one trans-vicinal proton. Spectral data of the compounds are discussed. Of particular interest is the inversion of the chemical shifts of exo- and endo-methylene protons when comparing the NMR.-spectra of anti- and syn-bishomoquinone.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19720550326
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