α-Arylation of Esters Catalyzed by the Pd(I) Dimer {[P(<i>t-</i>Bu)<sub>3</sub>]PdBr}<sub>2</sub>
作者:Takuo Hama、John F. Hartwig
DOI:10.1021/ol8002578
日期:2008.4.1
Conditions for the coupling of bromoarenes with esters using a single base and catalyst with improved turnovernumbers are described. These general conditions were made possible by using the Pd(I) catalyst [P(t-Bu)3]PdBr}2. Reactions of acetates, propionates, and isobutyrates are presented, and reactions of all three classes of esters on a 10 g scale are described.
Palladium-Catalyzed α-Arylation of Zinc Enolates of Esters: Reaction Conditions and Substrate Scope
作者:Takuo Hama、Shaozhong Ge、John F. Hartwig
DOI:10.1021/jo401476f
日期:2013.9.6
The intermolecular α-arylation of esters by palladium-catalyzed coupling of aryl bromides with zinc enolates of esters is reported. Reactions of three different types of zinc enolates have been developed. α-Arylation of esters occurs in high yields with isolated Reformatsky reagents, with Reformatsky reagents generated from α-bromo esters and activated zinc, and with zinc enolates generated by quenching
报道了通过芳基溴化物与酯的烯醇锌的钯催化偶联实现酯的分子间α-芳基化。已经开发出三种不同类型的烯醇锌的反应。使用分离的 Reformatsky 试剂、使用由 α-溴代酯和活化锌生成的 Reformatsky 试剂以及使用氯化锌猝灭酯的碱金属烯醇化物生成的锌烯醇化物,可以高产率进行酯的 α-芳基化。使用烯醇锌代替碱金属烯醇化物大大扩展了酯的芳基化范围。该反应在室温或 70 °C 下与含有氰基、硝基、酯、酮、氟、烯醇化氢、羟基或氨基官能团的溴代芳烃以及与溴代吡啶发生。酯的范围包括无环乙酸酯、丙酸酯和异丁酸酯、α-烷氧基酯和内酯。使用带有受阻五苯基二茂铁基二叔丁基膦(Q-phos)或高反应性二聚Pd(I)络合物[P( t -Bu) 3 ]PdBr} 2 的催化剂进行酯的烯醇锌的芳基化。