Recent Advances in Chiral Phosphoric Acid Catalyzed Asymmetric Reactions for the Synthesis of Enantiopure Indole Derivatives

Chiral indole derivatives are an intriguing class of heterocyclic compounds; their structural motifs are frequently found in natural products and synthetic compounds with significant bioactivity. Among many synthetic transformations leading to the production of enantiopure indole derivatives, chiral phosphoric acid catalyzed reactions are the most attractive methodologies, since these reactions can directly afford enantiomerically pure indole derivatives from readily accessible starting materials under mild conditions. In this review, the most recent achievements in this research area have been gathered and classified according to different reaction types for the synthesis of enantioenriched indole derivatives under the catalysis of chiral phosphoric acids. 1 Introduction 2 Chiral Phosphoric Acid Catalyzed Asymmetric Addition Reactions 2.1 1,2-Addition Reactions 2.2 1,4-Addition Reactions 3 Chiral Phosphoric Acid Catalyzed Asymmetric Cycloaddition Reactions 3.1 [3+2] Reactions 3.2 [4+2] Reactions 3.3 [3+3] Reactions 4 Chiral Phosphoric Acid Catalyzed Asymmetric Cascade Reactions 4.1 Cascade Reactions 4.2 Transition-Metal-Cocatalyzed Cascade Reactions 4.3 Other Organocatalyst-Cocatalyzed Cascade Reactions 5 Other Reactions Catalyzed by Chiral Phosphoric Acids 5.1 Aza-Claisen Rearrangement 5.2 Kinetic Resolution 5.3 Fischer Indolization 6 Conclusions and Perspective