One-Pot Sequential Hydrogenation and Kinetic Resolution: Simultaneous Synthesis of Two Classes of Optically Active N-Heterocycles

Abstract

Dihydropyrrolo[1,2-a]quinoxalines are important structural motifs widely present in natural products and biologically active molecules. Despite various well-developed racemic protocols, the enantioselective synthesis of optically active dihydropyrrolo[1,2-a]quinoxalines via asymmetric catalysis has been relatively less studied. In this work, a borane-catalyzed hydrogenation of pyrrolo[1,2-a]quinoxalines and a chiral phosphoric acid-catalyzed oxidative kinetic resolution of the resulting racemic dihydropyrrolo[1,2-a]quinoxalines via transfer hydrogenation have been successfully integrated into a one-pot process. A variety of optically active dihydropyrroquinoxalines and dihydrobenzoxazinones were obtained simultaneously with high levels of yields and ee's. Notably, this sequential process provides a straightforward method for synthesizing enantioenriched dihydropyrrolo[1,2-a]quinoxaline derivative, which acts as potent agricultural fungicides. The present work combines frustrated Lewis pair-catalyzed hydrogenation and chiral phosphoric acid-catalyzed transfer hydrogenation, providing a facile and efficient method for the simultaneous synthesis of two distinct classes of optically active nitrogen-containing heterocycles.

Keywords

Heterocycles / Asymmetric catalysis / Hydrogenation / Kinetic resolution / Frustrated Lewis pair / Chiral phosphoric acid / Pyrrolo[1,2-a]quinoxalines / Dihydropyrrolo[1,2-a]quinoxalines

RIGHTS & PERMISSIONS

2026 SIOC, CAS, Shanghai, & WILEY-VCH GmbH