State Key Laboratory of Chirosciences and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University , Hung Hom, Kowloon, Hong Kong.
Org Lett. 2017 Apr 21;19(8):2082-2085. doi: 10.1021/acs.orglett.7b00677. Epub 2017 Apr 4.
A Pd-catalyzed decarboxylative acylation of aromatic ketones with α-oxocarboxylic acids was developed, and 1,2-diacylbenzenes were formed in up to 90% yield with excellent ortho-selectivity. This work demonstrates the first successful attempt to direct C-H acylation of aromatic ketones without the need for prederivatization to imines. The acylation reaction was inhibited by radical scavengers such as TEMPO, and 2,2,6,6-tetramethylpiperidin-1-yl benzoate, the adduct of TEMPO and a benzoyl radical, has been isolated and characterized. This finding is compatible with the intermediacy of acyl radicals. A mechanism involving the reaction of the palladacyclic complexes of aryl ketones with acyl radicals is proposed.
发展了一种钯催化的芳酮与α-氧代羧酸的脱羧酰化反应，以高达 90%的收率和极好的邻位选择性得到了 1,2-二芳基苯。这项工作首次成功地尝试了在无需预先将芳酮衍生为亚胺的情况下直接进行 C-H 酰化反应。酰化反应被自由基清除剂如 TEMPO 和 2,2,6,6-四甲基哌啶-1-基苯甲酸酯抑制，后者是 TEMPO 和苯甲酰自由基的加合物，已经被分离并进行了表征。这一发现与酰基自由基的存在相兼容。提出了一种涉及芳酮的钯环合复合物与酰基自由基反应的机理。
