Department of Applied Chemistry, Faculty of Engineering, Osaka University , Suita, Osaka 565-0871, Japan.
J Am Chem Soc. 2015 Feb 4;137(4):1593-600. doi: 10.1021/ja511622e. Epub 2015 Jan 21.
The rhodium-catalyzed reaction of aryl 2-pyridyl ethers with a diboron reagent results in the formation of arylboronic acid derivatives via activation of the C(aryl)-O bonds. The straightforward synthesis of 1,2-disubstituted arenes was enabled through catalytic ortho C-H bond functionalization directed by the 2-pyridyloxy group followed by substitution of this group with a boryl group. Several control experiments revealed that the presence of a sp(2) nitrogen atom at the 2-position of the substrate and the use of a boron-based reagent were crucial for the activation of the relatively inert C(aryl)-O bond of aryl 2-pyridyl ethers.
铑催化的芳基 2-吡啶基醚与二硼试剂反应，通过活化 C(芳基)-O 键，生成芳基硼酸衍生物。通过 2-吡啶氧基的导向催化邻位 C-H 键功能化，随后用硼基取代该基团，可直接合成 1,2-二取代芳烃。通过几个对照实验发现，底物 2-位上的 sp(2)氮原子的存在以及使用基于硼的试剂对于活化芳基 2-吡啶基醚的相对惰性的 C(芳基)-O 键是至关重要的。
