Halodeacylation of aryl ketones

Beirne, J.J.; Coyle, A. M.; Donnelly, John A.

doi:10.1016/s0040-4020(01)92959-x

Cited by 10 publications

(1 citation statement)

References 12 publications

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“…Interestingly, ipso-substitution was also noticed in the case of the considerably electron-rich aryl ketone 2'-methyl-4',5'-dimethoxyacetophenone 23, in which the main bromodeacylated product 24 was accompanied by a small amount of α-bromoketone 25 (entry 8). Bromodeacylation is rather a rare process, known to take place with molecular bromine in a solution (Beirne et al 1970). The addition of TEMPO to the reaction mixture resulted in different effects for different substrates.…”

Section: Resultsmentioning

confidence: 99%

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

Grjol¹,

Jereb

2021

Chem. Pap.

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

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Section: Resultsmentioning

confidence: 99%