Chiral Phosphoric Acid-Catalyzed C6 Functionalization of 2,3-Disubstituted Indoles for Synthesis of Heterotriarylmethanes

The direct regio- and enantioselective C6 function-alization of 2,3-disubstituted indoles with azadienes has been developed using chiral phosphoric acid as catalyst, providing a convenient approach to synthesize the optically active heterotriaryl-methanes with excellent yields, broad substrate scope, and up to 98% ee. Mechanistic studies revealed that N-alkylation of 2,3-disubstituted indoles with azadienes would be reversible, and enantioselective C6 functionalization could be enabled.

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The study presents a method for direct regio- and enantioselective C6 functionalization of 2,3-disubstituted indoles with azadienes using chiral phosphoric acid as catalyst. Mechanistic studies show that N-alkylation of 2,3-disubstituted indoles with azadienes is reversible, enabling enantioselective C6 functionalization.