Non-directed highly para-selective C-H functionalization of TIPS-protected phenols promoted by a carboxylic acid ligand  

作　　者：Jingyao Geng Zhang Fang Guangliang Tu Yingsheng Zhao 

机构地区：[1]Key Laboratory of Organic Synthesis of Jiangsu Province,College of Chemistry,Chemical Engineering and Materials Science,Soochow University,Suzhou 215123,China [2]School of Chemistry and Chemical Engineering,Henan Normal University,Xinxiang 453000,China

出　　处：《Chinese Chemical Letters》2023年第3期342-346,共5页中国化学快报（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.21772139);the Jiangsu Province Natural Science Found for Distinguished Young Scholars(No.BK20180041);the PAPD Project;supported by the Open Research Fund of the School of Chemistry and Chemical Engineering,Henan Normal University。

摘　　要：Palladium-catalyzed non-directed C-H functionalization provides an efficient approach for direct functionalization of arenes, but it usually suffers from poor site selectivity, limiting its wide application.Herein, it is reported for the first time that the carboxylic acid ligand of 3,5-dimethyladamantane-1-carboxylic acid(1-DMAd CO_(2)H) can affect the site selectivity during the C-H activation step in palladiumcatalyzed non-directed C-H functionalization, leading to highly para-selective C-H olefination of TIPSprotected phenols. This transformation displayed good generality in realizing various other para-selective C-H functionalization reactions such as halogenation, and allylation reactions. A wide variety of phenol derivatives including bioactive molecules of triclosan, thymol, and propofol, were compatible substrates,leading to the corresponding para-selective products in moderate to good yields. A preliminary mechanism study revealed that the spatial repulsion factor between carboxylic acid ligand and bulky protecting group resulted in the selective C-H activation at the less sterically hindered para-position. This new model non-directed para-selective C-H functionalization can provide a straightforward route for remote site-selective C-H activations.

关 键 词：para-Selective Non-directed C-H olefination 

分 类 号：O641.4[理学—物理化学] O621.251[理学—化学]