Ligand-Enabled, Copper-Promoted Regio- and Chemoselective Hydroxylation of Arenes, Aryl Halides, and Aryl Methyl Ethers

We report here a practical method for the ortho C–H hydroxylation of benzamides with inexpensive copper­(II) acetate monohydrate and a pyridine ligand. An intra- and intermolecular ligand combination was explored to achieve regio- and chemoselective hydroxylation. Interestingly, typical regiochemical scrambling associated with the C–H activation was further resolved by introducing a ligand-directed ortho hydroxylation of haloarenes and aryl methyl ethers.本文报道了一种实用合成方法，以廉价易得的一水合乙酸铜(II)（copper(II) acetate monohydrate）与吡啶配体（pyridine ligand）为反应试剂，实现苯甲酰胺类化合物的邻位C-H羟基化（ortho C–H hydroxylation）。本研究通过探究分子内与分子间的配体组合策略，成功达成了兼具区域选择性与化学选择性的羟基化反应。值得注意的是，C-H活化（C–H activation）过程中常见的典型区域选择性混杂问题，可通过引入配体导向的卤代芳烃（haloarenes）与芳基甲基醚（aryl methyl ethers）邻位羟基化策略得到进一步解决。