Polarity Controlled Reversal of 5-Exo/6-endo-Selectivities in the Synthesis of β-Brominated Cyclic Ethers

Thomas Gottwald; Marco Greb; Jens Hartung

doi:10.1055/s-2003-43378

LETTER

Polarity Controlled Reversal of 5-Exo/6-endo-Selectivities in the Synthesis of β-Brominated Cyclic Ethers

Thomas Gottwald^a, Marco Greb^a, Jens Hartung*^b
^a Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
^b Fachbereich Chemie, Organische Chemie, Universität Kaiserslautern, Erwin-Schrödinger Straße, 67663 Kaiserslautern, Germany
Fax: +49(631)2053921; e-Mail: hartung@chemie.uni-kl.de;

Abstract

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Abstract

Polar bromocyclizations of bishomoallylic alcohols (nucleophilic oxygen), which have methyl and/or phenyl substituents located at positions 1, 4, and/or 5, and cyclizations of the derived alkenoxyl radicals (electrophilic oxygen) followed by bromine atom trapping from BrCCl₃, proceed with complementary regioselectivities.

Key words

alkoxyl radical - bromide oxidation - tert-butyl hydroperoxide - Mitsunobu reaction - vanadium

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References

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