Visible-Light-Promoted Wohl–Ziegler Functionalization of Organic Molecules with N-Bromosuccinimide under Solvent-Free Reaction Conditions

✍ Scribed by Marjan Jereb; Marko Zupan; Stojan Stavber

• Book ID: 102256859
• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: German
• Weight: 210 KB
• Volume: 92
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200800308

✦ Synopsis

Abstract

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The visible‐light‐induced transformation of toluenes with N‐bromosuccinimide (NBS) under solvent‐free reaction conditions (SFRC) was studied. The reaction took place in spite of the very restricted molecular motion; toluenes could be regioselectively converted to benzyl bromides. Selective radical‐chain reactions with NBS were carried out in liquid/liquid and in solid/solid systems; furthermore, reactions could be performed in the presence of air. The radical scavenger TEMPO (=2,2,6,6‐tetramethylpiperidin‐1‐yloxy) completely suppressed the side‐chain bromination of toluenes with NBS under SFRC. Electron‐withdrawing groups decreased the reactivity of the toluenes, and the Hammett reaction constant ρ^+^=−1.7 indicated involvement of polar radical intermediates with electrophilic character.