The poor will be rich: BFPy phosphanes (see scheme) mimic the electronic and steric characters of P(C6F5)3 and PPh3, respectively. These novel ligands showed a large ligand acceleration effect on Stille coupling, the Rh‐catalyzed 1,2‐addition of aryl boronic acid to unactivated ketones and the asymmetric arylation of N‐tosylimine using phenylboronic acid.
穷人将变得富有:BFPy膦(参见方案)分别模仿P(C 6 F 5)3和PPh 3的电子和位阻特征。这些新颖的配体对Stille偶联,Rh催化的1,2-芳基硼酸加成到未活化的酮上以及N-甲苯磺胺使用苯基硼酸的不对称芳基化表现出很大的配体促进作用。
Electron-Poor Chiral Diphosphine Ligands: High Performance for Rh-Catalyzed Asymmetric 1,4-Addition of Arylboronic Acids at Room Temperature
Electron-poor chiral diphosphine ligands, MeO-F(28)-BIPHEP (1a) and MeO-F(12)-BIPHEP (1b), were synthesized for controlling a transition-metal catalyst electronically. The 1b-ligated Rh catalyst showed excellent catalytic activity with high % ee for asymmetric 1,4-addition of arylboronic acids to alpha,beta-unsaturated carbonyls at 20 degrees C. The strong pi-acceptor ability of 1b induces transmetalation of arylboronic acid to catalyst precursor [RhCl(1b)](2) directly in the first step of the catalytic cycle.