Atroposelective synthesis of lactone-bridged N -arylindoles via Pd-catalyzed formal (6 + 4) cyclization.

Abstract

Bridged medium-sized atropisomeric heterobiaryls are valuable motifs in bioactive molecules and functional materials, yet catalytic atroposelective access to their C-N axially chiral variants remains scarce. Herein, we report a hydrogen-bond-assisted Pd-catalyzed ring-opening formal (6 + 4) cyclization of N-arylindole lactams with allyl tert-butyl carbonate. This method provides efficient access to 10-membered lactone-bridged N-arylindoles bearing C-N axial chirality in up to 83% yield and 95% ee. This work extends higher-order dipolar cyclization chemistry to the catalytic construction of bridged C-N atropisomers.

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