Catalytic Wittig Reactions of Semi- and Nonstabilized Ylides Enabled by Ylide Tuning
作者:Emma E. Coyle、Bryan J. Doonan、Andrew J. Holohan、Killian A. Walsh、Florie Lavigne、Elizabeth H. Krenske、Christopher J. O'Brien
DOI:10.1002/anie.201406103
日期:2014.11.17
The first examples of catalytic Wittig reactions with semistabilized and nonstabilized ylides are reported. These reactions were enabled by utilization of a masked base, sodium tert‐butyl carbonate, and/or ylide tuning. The acidity of the ylide‐forming proton was tuned by varying the electron density at the phosphorus center in the precatalyst, thus facilitating the use of relatively mild bases. Steric
报道了具有半稳定和不稳定的叶立德的催化Wittig反应的第一个实例。这些反应可以通过使用掩蔽的碱,碳酸叔丁酯钠和/或内酯调节来实现。可以通过改变预催化剂中磷中心的电子密度来调节形成内酯的质子的酸度,从而有利于使用相对温和的碱。对前催化剂结构的立体修饰导致E 选择性显着提高,达到> 95:5(E / Z)。