Electrochemical chlorination and bromination of electron-deficient C H bonds in quinones, coumarins, quinoxalines and 1,3-diketones
作者:Dan Yu、Ruixue Ji、Zhihui Sun、Wenjie Li、Zhong-Quan Liu
DOI:10.1016/j.tetlet.2021.153514
日期:2021.12
The electrochemistry-promoted chlorination and bromination of electron-deficient CH bonds was developed, using quinones, coumarins, quinoxalines and 1,3-diketones. This protocol features readily available and safe halogen sources (hydrochloric acid and KBr), high site-selectivity and mild reaction conditions. It could provide an efficient access to a series of chlorinated and brominated quinones, coumarins
Halogenated ketenes. 39. A new synthesis for substituted coumarins
作者:William T. Brady、C. H. Shieh
DOI:10.1002/jhet.5570210518
日期:1984.9
A new general synthesis of substituted coumarins is described. The in situ cycloaddition of chloroketenes with α-methoxymethylenecyclohexanones yields (4 + 2) cycloaddition products, 3,4-dihydro-2-pyranones. The chlorine atom is reductively removed and methanol is spontaneously eliminated to yield the 5,6,7,8-tetra-hydrocoumarins. Dehydrogenation of these compounds results in good yields of the substituted
efficient, regioselectivechlorination of coumarins using Earth-abundant and cost-effective CuCl2 under visible light irradiation is reported. A key feature of this protocol is the photocatalytic dissociation of the copper(II) complex in acetonitrile through ligand-to-metal charge transfer (LMCT) to give the chlorine atom which then selectively chlorinates the coumarin. This method can chlorinate a broad
报道了在可见光照射下使用地球丰富且具有成本效益的 CuCl 2对香豆素进行有效的区域选择性氯化。该协议的一个关键特征是通过配体到金属电荷转移 (LMCT) 将乙腈中的铜 ( II ) 配合物光催化解离,从而产生氯原子,然后选择性地氯化香豆素。该方法可以用吸电子或给电子取代基对范围广泛的香豆素进行氯化,以区域选择性地提供 3-氯香豆素,并以良好至优异的产率进一步扩展到其他缺电子杂环和烯烃,例如黄酮、8-甲氧基补骨脂素和萘醌。
Borse, Arvind P.; Kelkar, Shriniwas L.; Wadia, Murban S., Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 1987, vol. 26, # 1-12, p. 1180 - 1181
作者:Borse, Arvind P.、Kelkar, Shriniwas L.、Wadia, Murban S.