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Full Paper
Association of Fluorous “Phase-Vanishing” Method with Visible-Light Activation in Benzylic Bromination by Bromine
Article first published online: 3 NOV 2005
DOI: 10.1002/ejoc.200500355
Copyright © 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Additional Information
How to Cite
Podgoršek, A., Stavber, S., Zupan, M. and Iskra, J. (2006), Association of Fluorous “Phase-Vanishing” Method with Visible-Light Activation in Benzylic Bromination by Bromine. Eur. J. Org. Chem., 2006: 483–488. doi: 10.1002/ejoc.200500355
Publication History
- Issue published online: 2 JAN 2006
- Article first published online: 3 NOV 2005
- Manuscript Received: 18 MAY 2005
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Keywords:
- Halogenation;
- Perfluorinated solvents;
- Radical reactions;
- Phase transitions;
- Fluorous chemistry
Abstract
In this study the “phase-vanishing” method for diffusion-controlled addition of a reagent (Br2) to a reaction phase via a fluorous membrane (C8F18) is combined with an additional mode of activation (visible-light) to achieve the benzyl bromination of various alkyl-substituted aromatic compounds in a concentrated solution. Benzyl bromination of p-tert-butyltoluene proceeded in various solvents including hexane and methanol, while the reaction of the neat substrate showed a similar selectivity as in carbon tetrachloride. The effect of the substituent on the para position of toluene on the course of bromination revealed three processes: benzyl bromination with H, Me, tBu and CO2Et substituents, aromatic bromination with OMe and NHAc substituents and the reaction of the 4-acetyl derivative at the substituent to form an α-bromo ketone.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)