γ-Selective Cross-Coupling of Allylic Silanolate Salts with Aromatic Bromides Using Trialkylphosphonium Tetrafluoroborate Salts Prepared Directly from Phosphine•Borane Adducts
作者:Scott E. Denmark、Nathan S. Werner
DOI:10.1021/ol2017998
日期:2011.9.2
γ-selective, palladium-catalyzed cross-coupling of sodium (Z)-2-butenyldiethylsilanolate with a variety of aromatic bromides is reported. The protocol provides high yields (73–94%) and site selectivity (γ/α, 25:1 → > 99:1) in the coupling of electron-rich, electron-poor, sterically hindered, and heteroaromatic bromides. The use of a configurationally homogeneous (Z)-silanolate, nontransferable ethyl groups
报道了γ 选择性、钯催化的 ( Z )-2-丁烯基二乙基硅烷醇钠与多种芳香族溴化物的交叉偶联。该协议在富电子、缺电子、空间位阻和杂芳族溴化物的耦合中提供了高产率 (73–94%) 和位点选择性 (γ/α, 25:1 → > 99:1)。使用由相应的空气稳定膦•硼烷加合物直接制备的构型均匀的 ( Z )-硅烷醇化物、不可转移的乙基和空间庞大的三烷基鏻四氟硼酸盐 ( t -BuCy 2 PH + BF 4 – ) 对方法的成功。