Chiral-Phosphoric-Acid-Catalyzed C6-Selective Pictet–Spengler Reactions for Construction of Polycyclic Indoles Containing Spiro Quaternary Stereocenters
Xinwei Wang, Wen‐Jun Huang, Han Wang, Bo Wu, Yong‐Gui Zhou
Abstract
Compared with the well-established asymmetric Pictet–Spengler reactions on the pyrrole ring of indoles, the catalytic asymmetric Pictet–Spengler reaction on the benzene ring of indoles has been rarely studied. Herein the C6-selective Pictet–Spengler reactions of indoles have been realized by employing 2-(1H-indol-7-yl)anilines and isatins in the presence of chiral phosphoric acid, affording novel polycyclic indole derivatives bearing spiro quaternary stereocenters in excellent yields with excellent enantioselectivities. This reaction could be conducted on the gram scale without any loss of activity or enantioselectivity.
Topics & Concepts
StereocenterChemistryIndole testPhosphoric acidCatalysisPictet–Spengler reactionPyrroleRing (chemistry)Organic chemistryCombinatorial chemistryEnantioselective synthesisAlkaloids: synthesis and pharmacologyAsymmetric Synthesis and CatalysisAxial and Atropisomeric Chirality Synthesis