Reactivity of substrates with multiple competitive reactive sites toward NBS under neat reaction conditions promoted by visible light

Abstract Regioselectivity of visible-light-induced transformations a range (hetero)aryl alkyl-substituted ketones bearing several competitive reactive sites ( ? -carbonyl, benzyl and aromatic ring) with N- bromosuccinimide (NBS) was studied under solvent-free reaction conditions (SFRC) in the absence inert-gas atmosphere, radical initiators catalysts. An 8-W energy-saving household lamp used for irradiation. Heterogeneous were dealt throughout study. All substrates mono- or dibrominated at -carbonyl position, additionally, some benzylic bromination observed carbon atoms electron-donating methoxy groups, respectively. Surprisingly, ipso -substitution acyl group bromine atom took place (4-methoxynaphthyl) alkyl ketones. While addition scavenger TEMPO (2,2,6,6-tetramethylpiperidin-1-yloxy) decreased extent - ring bromination, it completely suppressed , -dibromination NBS SFRC.