Asymmetric Intramolecular Amination Catalyzed with Cp*Ir-SPDO via Nitrene Transfer for Synthesis of Spiro-Quaternary Indolinone
Shiqiang Wei, Zihao Li, Shuanghu Wang, Hua Chen, Xiao-Yu Wang, Yun-Zhou Gu, Ye Zhang, Hong Wang, Tong‐Mei Ding, Shu‐Yu Zhang, Yong‐Qiang Tu
Abstract
An asymmetric intramolecular spiro-amination to high steric hindering α -C–H bond of 1,3-dicarbonyl via nitrene transfer using inactive aryl azides has been carried out by developing a novel Cp*Ir(III)-SPDO (spiro-pyrrolidine oxazoline) catalyst, thereby enabling the first successful construction of structurally rigid spiro-quaternary indolinone cores with moderate to high yields and excellent enantioselectivities. DFT computations support the presence of double bridging H–F bonds between [SbF 6 ] − and both the ligand and substrate, which favors the plane-differentiation of the enol π-bond for nitrenoid attacking. These findings open up numerous opportunities for the development of new asymmetric nitrene transfer systems.