School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi 530004, China.
Org Biomol Chem. 2022 Aug 24;20(33):6667-6672. doi: 10.1039/d2ob01134d.
An efficient, regioselective chlorination of coumarins using Earth-abundant and cost-effective CuCl 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 scope of coumarins with either electron-withdrawing or electron-donating substituents to regioselectively afford 3-chlorocoumarins in good to excellent yields and can be further extended to other electron-deficient heterocycles and olefins such as flavones, 8-methoxypsoralen and naphthoquinones.
本文报道了一种在可见光照射下使用丰富且廉价的 CuCl 实现香豆素高效、区域选择性氯化的方法。该方法的一个特点是通过配体到金属电荷转移（LMCT）使乙腈中的铜（II）配合物光解，从而产生氯原子，该氯原子选择性地氯化香豆素。该方法可以对具有吸电子或给电子取代基的广泛范围的香豆素进行区域选择性氯化，以良好至优异的收率得到 3-氯香豆素，并且可以进一步扩展到其他缺电子杂环和烯烃，如黄酮类、8-甲氧基补骨脂素和萘醌。
