Asymmetric aza‐Friedel–Crafts Reaction of Cyclic Ketimines with 5‐Aminopyrazole Derivatives: Expedient Access to Pyrazole‐Based C2‐quaternary Indolin‐3‐Ones
Xiu‐Xiu Qiao, Yonghui He, Tao Ma, Changpeng Zou, Xixi Wu, Ganpeng Li, Xiaojing Zhao
Abstract
A chiral phosphoric acid-catalyzed enantioselective aza-Friedel-Crafts reaction of 5-aminopyrazole derivatives with cyclic ketimines attached to a neutral functional group is reported. This protocol allows the formation of pyrazole-based C2-quaternary indolin-3-ones with high enantioselectivities and regioselectivities. Moreover, gram-scale synthesis of the 5-aminopyrazole-based C2-quaternary indolin-3-ones was performed, with no decrease in the yield and enantioselectivity.
Topics & Concepts
Friedel–Crafts reactionPhosphoric acidEnantioselective synthesisChemistryPyrazoleYield (engineering)CatalysisOrganic chemistryCombinatorial chemistryMaterials scienceMetallurgyAsymmetric Synthesis and CatalysisChemical Synthesis and AnalysisSynthesis and Catalytic Reactions