Sonochemical bromination of acetophenones using p-toluenesulfonic acid–N-bromosuccinimide

Adhikari, M.; Samant, Shriniwas D.

doi:10.1016/s1350-4177(01)00108-0

Cited by 42 publications

(9 citation statements)

References 7 publications

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“…In our process, it seems that NCS was not more efficient than DCDMH. Samant et al 24 suggested the mechanism of keto-enol tautomerism in the process of the bromination of substituted acetophenones using NBS and we thought the mechanism of our processes was possibly similar to the one that Samant et al mentioned.…”

Section: Resultssupporting

confidence: 62%

Simple and efficient methods for selective preparation of α-mono or α,α-dichloro ketones and β-ketoesters by using DCDMH

et al. 2009

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New processes that can selectively prepare a-mono or a,a-dichloro ketones and b-ketoesters using 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) are reported. Using silica gel as the catalyst and methanol as the solvent and heating for 1 h under reflux, a-monochlorinated products were selectively obtained in 86-98% yield. However using a deep eutectic solvent (choline chloride: p-TsOH = 1:1) as the solvent and stirring for 45 min at room temperature, a,a-dichlorinated products were selectively obtained in 86-95% yield.

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Section: Resultssupporting

confidence: 62%

Simple and efficient methods for selective preparation of α-mono or α,α-dichloro ketones and β-ketoesters by using DCDMH

et al. 2009

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“…Synthesis of 3-styrylcoumarins was performed following the scheme 1, which began with formation of the coumarin (2) by microwave assisted Pechmann reaction between resorcinol (1) and ethyl acetoacetate (Manhas et al, 2006). Compound (3), obtained by microwave assisted Williamson etherification reaction of coumarin (2) (Otero et al, 2014) in 85% yield, was brominated with NBS (Adhikari et al, 2002) to give the alkyloxybromocoumarin (4) in 75% yield. This compound was subjected to cross-coupling with various styrenes (5) under palladium catalysis (Heck reaction) (Sabrina et al, 2011), leading to the formation of seven 3-styrylcoumarins (6a-6g) in 35%-49% yields.…”

Section: Synthesis Of 3-styrylcoumarinsmentioning

confidence: 99%

Synthesis and antiproliferative activity of 3- and 7-styrylcoumarins

et al. 2018

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A series of styrylcoumarins were obtained via Mizoroki-Heck reactions between 3-bromo-4-methyl-7-(octyloxy)-2H-chromen-2-one or 2-oxo-2H-chromen-7-yl trifluoromethanesulfonate and functionalized styrenes. The structures of the products were elucidated by spectroscopic analysis. All compounds were evaluated against SW480 and CHO-K1 cell lines. A number of hybrids showed good antiproliferative activity. Among the tested compounds, hybrids 6e, 10c and 10d, exhibited the highest activity (IC50-SW480/48h = 6,92; 1,01 and 5,33 µM, respectively) and selectivity (IS48h = >400; 67,8 and 7,2, respectively). In addition, these compounds were able to preserve their activities over time. The results achieved by these hybrids were even better than the lead compounds (coumarin and resveratrol) and the standard drug (5-FU). As regards structure-activity relationship it seems that the location of the styryl group on the coumarin structure and the presence of the hydroxyl group on the phenyl ring were determinant for the activity.

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“…On water, 4'-bromomethylacetophenone was the only product formed (Podgoršek et al 2009), whereas the treatment of 1a with NBS/SiCl 4 in MeCN furnished the compound 3a as the sole product (Salama and Novák 2011). Conversely, compound 1a was selectively α-brominated using NBS/PTSA under ultrasound irradiation in methanol (Adhikari and Samant, 2002). In contrast to the straight-chain functionalized derivatives, at the branched isopropyl 1c and cyclohexyl 1d acetophenones only α-bromination took place with no benzylic bromination observed (entries 4 and 5).…”

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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Sonochemical bromination of acetophenones using p-toluenesulfonic acid–N-bromosuccinimide

Cited by 42 publications

References 7 publications

Simple and efficient methods for selective preparation of α-mono or α,α-dichloro ketones and β-ketoesters by using DCDMH

Simple and efficient methods for selective preparation of α-mono or α,α-dichloro ketones and β-ketoesters by using DCDMH

Synthesis and antiproliferative activity of 3- and 7-styrylcoumarins

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

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