Carbon tetrachloride free benzylic brominations of methyl aryl halides

Abstract

A series of mono- and dimethyl aryl halides was α-brominated with NBS using either light-induction or microwave-assistance. Instead of the commonly used CCl₄ or other chlorinated solvents, MeOAc was used as an environmentally more benign solvent for these side-chain bromination reactions. Moreover, in MeOAc the use of initiator was not required, while the product yields were comparable. With microwave-assistance various benzylic bromides became accessible in short reaction times via direct α-bromination of the corresponding arenes. Finally, aryl halides that were unreactive in CCl₄ could be brominated in moderate to good yields in MeOAc under microwave conditions.