Chiral Heterogeneous Scandium Lewis Acid Catalysts for Continuous‐Flow Enantioselective Friedel–Crafts Carbon–Carbon Bond‐Forming Reactions. Issue 51 (9th November 2021)

• Record Type: Journal Article
• Authors: Saito, Yuki; Kobayashi, Shū
• Is Part Of: Angewandte Chemie international edition. Volume 60:Issue 51(2021)
• Page Start: 26566
• Page End: 26570
• Publication Date: 2021-11-09
• Subjects: asymmetric catalysis -- flow synthesis -- Friedel–Crafts reaction -- heterogeneous catalysis -- Sc catalysts; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202112797
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: While continuous‐flow reactions with chiral heterogeneous catalysts provide a highly efficient method to synthesize optically active compounds, chiral heterogeneous Lewis acid catalysis has been less extensively explored. We have developed the first example of chiral heterogeneous Sc catalysts, which demonstrated excellent activity and selectivity for continuous‐flow enantioselective Friedel–Crafts reactions of isatins with indoles. Noncovalent interactions between chiral Sc complexes and heteropoly acid‐anchored amine‐functionalized SiO2 as support were utilized for the synthesis. The heteropoly acid was found to be crucial for the preparation, activity, and selectivity of the catalysts. The chiral ligand could be easily tuned without chemical modification and the continuous‐flow synthesis of a biologically active compound was achieved. Abstract : Chiral heterogeneous Sc catalysts that demonstrate excellent activity and selectivity for continuous‐flow enantioselective Friedel–Crafts reactions of isatins with indoles have been developed. Noncovalent interactions between chiral Sc complexes and heteropoly acid‐anchored amine‐functionalized SiO2 as support were utilized for the preparation. Continuous‐flow synthesis of a biologically active compound was achieved by tuning the chiral ligands.