手性磷酸控制的不对称碳氢芳基化反应合成平面手性二茂铁化合物

Asymmetric C—H Arylation for the Synthesis of Planar Chiral Ferrocenes: Controlling Enantioselectivity Using Chiral Phosphoric Acids

报道了钯催化的分子内不对称C—H键芳基化反应.以简单易得的二茂铁羰基化合物为底物,Pd(CH_3CN)_4(OTf)_2为催化剂,使用手性磷酸作为唯一手性源,Buchwald类型联苯单膦配体,甲苯作溶剂,100℃进行反应,得到一系列二茂铁化合物,ee值最高可达83%.该反应为合成平面手性二茂铁化合物提供了一种新途径.

Transition-metal-catalyzed direct activation reactions of unreactive C—H bond has been extensively developed in recent years. Although numerous synthetic methods have been reported to build diverse complex compounds, enantioselective C—H activation has not been paid much attention probably because of the absence of suitable ligands to control the stereoselectivity in the C—H activation reaction. Herein, a Pd（0）-catalyzed enantioselective synthesis of planar chiral ferrocenes was described, and chiral phosphoric acids were used as the only chiral source to control the stereoselectivity in the C—H activation reactions.