- 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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- A novel 3-chloro-coumarin derivatives preparation method (by machine translation)
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The invention discloses a novel 3-chloro-coumarin derivatives of the preparation method, comprising the following operations: the coumarin derivatives as a chlorine source of the N-chloro succinimide (NCS) mixed, dissolved in an organic solvent, in the presence of salt catalyst, 82-200 °C reflux reaction 8-45h preparation of 3-chloro-coumarin derivatives. The method of the invention for preparing the resulting 3-chloro-coumarin derivatives, the ace can reach its yield is 95.5%, note the method of the invention has very good regioselectivity. And the method of the invention the raw material is easy to obtain, reaction is easy to control, after-treatment is simple and convenient the low characteristic of toxicity. (by machine translation)
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Paragraph 0035; 0036; 0037; 0038; 0039; 0040; 0041-0044
(2016/10/10)
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- A metal-free one-pot synthesis of benzo[: C] chromen-6-ones from 3,4-dichlorocoumarins and butadienes using tandem photo-thermal-photo reactions
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An efficient, simple and versatile synthesis of biologically valuable benzo[c]chromen-6-ones is achieved using a tandem photo-thermal-photo reaction sequence starting from 3,4-dichlorocoumarins and a 1,3-butadiene. In this concise one-pot protocol, neither metal catalyst nor peroxide promoter is needed and the products can be purified through simple recrystallization in most cases. The synthesis consists of a reaction sequence of photo-induced [4 + 2] and [2 + 2] cycloadditions, silica gel promoted elimination of HCl and electrocyclic cyclobutene ring opening followed by a photo-induced 6π electrocyclization. The reactions proceed well with a range of dichlorocoumarins and some typical butadienes to provide the corresponding annulated products in 70-80% yield.
- Zhang, Yan,Tian, Yan,Xiang, Pei,Huang, Ning,Wang, Jianyi,Xu, Jian-Hua,Zhang, Min
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supporting information
p. 9874 - 9882
(2016/10/31)
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