Efficient and facile catalytic protocols for chlorination and ligand-directed ortho-acetoxylation of 2-arylbenzoxazoles have been developed. The chlorination is not a ligand-directed ortho-functionalization, but an electrophilic substitution process in the benzo ring of the benzoxazole moiety. Meanwhile, the acetoxylation exhibited high regioselectivity for the substrates containing a meta-substituent and occurred at the less sterically hindered ortho-C–H bond of the directing group.
针对 2-芳基
苯并恶唑的
氯化和
配体定向正乙酰氧基化,我们开发出了高效、简便的催化方案。
氯化反应不是
配体定向的正官能化,而是
苯并恶唑分子苯环上的亲电取代过程。同时,乙酰氧基化对含有元取代基的底物具有很高的区域选择性,并且发生在指导基团的立体阻碍较小的正交-C-H 键上。