- Cooperativity within the catalyst: alkoxyamide as a catalyst for bromocyclization and bromination of (hetero)aromatics
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Alkoxyamide has been reported as a catalyst for the activation ofN-bromosuccinimide to perform bromocyclization and bromination of a wide range of substrates in a lipophilic solvent, where adequate suppression of the background reactions was observed. The key feature of the active site is the alkoxy group attached to the sulfonamide moiety, which facilitates the acceptance as well as the delivery of bromonium species from the bromine source to the substrates.
- Mondal, Haripriyo,Sk, Md Raja,Maji, Modhu Sudan
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supporting information
p. 11501 - 11504
(2020/10/12)
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- A Copper Halide Promoted Regioselective Halogenation of Coumarins Using N-Halosuccinimide as Halide Source
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A safe, convenient, and regioselective synthesis of 3-halo coumarins using a metal halide (CuX 2 alone or with ZnX 2) promoted halogenation with N -halosuccinimide (NXS) as halide source is reported. The synthesis involved the steady in situ generation of highly reactive positive halogen (X +) by the coordination of copper or zinc with the N -halosuccinimide and subsequent electrophilic aromatic substitution of the electron-deficient coumarins. This procedure works well also for the halogenation of less electron-rich naphthoquinones, flavones, and methoxypsoralen in moderate to quantitative yields. This protocol features simple experimental conditions using readily available inexpensive reagents and provides a convenient approach to the chlorination or bromination of some useful heteroaromatic compounds.
- Su, Jinling,Zhang, Yan,Chen, Mingren,Li, Weiming,Qin, Xuewei,Xie, Yanping,Qin, Lixiao,Huang, Shihua,Zhang, Min
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supporting information
p. 630 - 634
(2019/03/08)
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- Efficient synthesis of chromones with alkenyl functionalities by the heck reaction
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The usefulness of the Heck reaction in the field of chromones has been demonstrated. Bromochromones with the halogen atom in their rings A and B were reacted with various terminal alkenes to give hitherto unknown alkenyl-substituted chromones. Reactivity of the substrates was found to markedly depend on the position of the bromine atom. Under phosphine-free conditions using a phase-transfer catalyst additive (tetrabutylammonium bromide), shorter reaction periods and usually higher yields were obtained.
- Patonay, Tams,Vasas, Attila,Kiss-Szikszai, Attila,Silva, Artur M. S.,Cavaleiro, Jos A. S.
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p. 1582 - 1593
(2011/08/04)
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- Photochemical transformations in 1-(o-hydroxyaryl)-1,3-diketones
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Irradiation (using pyrex glass filter) of o-hydroxybenzoylacetophenone (1a), o-hydroxybenzoylacetone (1b), 2-hydroxy-1-naphthoylacetophenone (5a), 2-hydroxy-1-naphthoylacetone (5b) and 1-hydroxy-2-naphthoylacetone (9) in Br2/CHCl3 and I2/MeOH solutions leads to various chromone derivatives.Parallel reactions of these 1,3-diketones in the dark record no perceptible change in them.Enhanced photoenolisation of the diketones, in the presence of bromine or iodine, is deemed to be the key step in these transformations.
- Garg, S.,Ishar, M. P. S.,Sarin, R.,Gandhi, R. P.
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p. 1123 - 1128
(2007/10/02)
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