α-Bromo spiroketals: Stereochemistry and elimination reactions

Lawson E.N., Kitching W., Kennard C.H.L. and Byriel K.A. (1993) α-Bromo spiroketals: Stereochemistry and elimination reactions. Journal of Organic Chemistry, 58 9: 2501-2508.

Author Lawson E.N.
Kitching W.
Kennard C.H.L.
Byriel K.A.
Title α-Bromo spiroketals: Stereochemistry and elimination reactions
Journal name Journal of Organic Chemistry   Check publisher's open access policy
ISSN 0022-3263
Publication date 1993
Sub-type Article (original research)
Volume 58
Issue 9
Start page 2501
End page 2508
Total pages 8
Subject 1605 Policy and Administration
Abstract The simple spiroketals, 1,6-dioxaspiro[4.4]nonane (2), 1,6-dioxaspiro[4.5]decane (5), 1,7-dioxaspiro-[5.5]undecane (6), and (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane (7), have been brominated by bromine in carbon tetrachloride/calcium carbonate or acetic acid, and a number of mono-, di-, and tribromo derivatives have been characterized. The relative stereochemistries have been established by correlated 1H and 13C NMR spectroscopy and X-ray crystal structure determinations. Dehydrobromination with potassium tert-butoxide in either dimethyl sulfoxide or tetrahydrofuran is facile for the axial monobromides, although both axial and equatorial bromides derived from 1,6-dioxaspiro[4.5]decane (5) and 1,7-dioxaspiro[5.5]undecane (6) dehydrobrominate to provide 1,6-dioxaspiro[4.5]dec-9-ene (35) and 1,7-dioxaspiro[5.5]undec-4-ene (26), respectively. Hydration of these readily acquired alkenes furnishes the corresponding 9- and 4-ols, respectively, with the latter being components of the rectal glandular secretion of Bactrocera oleae (olive fly), Bactrocera cacuminatus, and Bactrocera distincta. These studies indicate that α-bromination of suitable spiroketals may be a viable later step in the synthesis of α-bromine-containing spiroketal metabolites such as obtusin and neoobtusin.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import
 
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