Polymer‐Supported Phosphoric‐Acid Catalysed Enantioselective Pictet‐Spengler Cyclisation for the Synthesis of Quaternary Tryptolines in Batch/Continuous Flow
作者:Moreshwar B. Chaudhari、Prachi Gupta、Patricia Llanes、Miquel A. Pericàs
DOI:10.1002/adsc.202201275
日期:2023.2.21
the reaction has been demonstrated in continuous flow, with a residence time of only 24 minutes. The robust immobilized catalyst has been recycled and reused multiple times in batch and flow. The synthesis of the chiral precursors of Tadalafil, the Iboga-type alkaloid (+)-Tabertinggine and antimalarial spiroindolinones has been achieved in batch and continuous-flow.
Enantioselective Pictet–Spengler reactions of isatins for the synthesis of spiroindolones
作者:Joseph J. Badillo、Abel Silva-García、Benjamin H. Shupe、James C. Fettinger、Annaliese K. Franz
DOI:10.1016/j.tetlet.2011.08.071
日期:2011.10
The condensation cyclization between isatins and 5-methoxy tryptamine catalyzed by chiral phosphoric acids provides spirooxindole tetrahydro-beta-carboline products in excellent yields (up to 99%) and enantioselectivity (up to 98:2 er). A comparison of catalysts provides insight for the substrate scope and factors responsible for efficient catalytic activity and selectivity in the spirocyclization. Chiral phosphoric acids with different 3,3'-substitution on the binaphthyl system and opposite axial chirality afford the spiroindolone product with the same absolute configuration. (C) 2011 Elsevier Ltd. All rights reserved.
An Easy Entry to Optically Active Spiroindolinones: Chiral Brønsted Acid-Catalysed Pictet-Spengler Reactions of Isatins
The first catalytic asymmetric Pictet–Spenglerreaction of isatins is presented. BINOL‐derived phosphoric acids were found to be competent catalysts for this transformation, giving challenging spirooxindole structures bearing a quaternary stereocentre with generally good results. The 1,2,3,4‐tetrahydro‐β‐carboline products (spiroindolinones) are the core of some newly discovered anti‐malarial agents