New axially chiral biaryl quinoline ligands specifically partnered with AgOTf enabled an enantioselective aza-Friedel-Crafts reaction.

Org Biomol Chem

Key Laboratory of Asymmetric Synthesis & Chirotechnology of Sichuan Province, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, P. R. China.

Published: April 2025


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Article Abstract

A new class of axially chiral biaryl pyridine ligands have been rationally designed and concisely prepared in two steps by Skraup-Doebner-Miller synthesis. Their proof-of-concept application in an enantioselective aza-Friedel-Crafts reaction between 2-methylindoles and isatin -Boc ketimines has been evaluated. Specifically partnered with AgOTf, the new ligands effectively catalysed the reaction with excellent enantioselectivities (up to 96% ee) and 71-94% yields, and a series of multifunctional chiral 3-indolyl 3-amino-oxindoles were successfully obtained. Compared with other noble metals and chiral ligands, this Ag(I)-B1 partner is highly stable, cost-effective, facile and easily available. This work has successfully demonstrated the good performance of a new kind of axially biaryl quinoline ligands and is the first example of a silver-catalysed enantioselective aza-Friedel-Crafts reaction between 2-methylindoles and isatin -Boc ketimines, and has thus enriched the application of silver salts in asymmetric catalysis.

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http://dx.doi.org/10.1039/d5ob00231aDOI Listing

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New axially chiral biaryl quinoline ligands specifically partnered with AgOTf enabled an enantioselective aza-Friedel-Crafts reaction.

Org Biomol Chem

April 2025

Key Laboratory of Asymmetric Synthesis & Chirotechnology of Sichuan Province, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, P. R. China.

A new class of axially chiral biaryl pyridine ligands have been rationally designed and concisely prepared in two steps by Skraup-Doebner-Miller synthesis. Their proof-of-concept application in an enantioselective aza-Friedel-Crafts reaction between 2-methylindoles and isatin -Boc ketimines has been evaluated. Specifically partnered with AgOTf, the new ligands effectively catalysed the reaction with excellent enantioselectivities (up to 96% ee) and 71-94% yields, and a series of multifunctional chiral 3-indolyl 3-amino-oxindoles were successfully obtained.

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