Chiral Benzimidazole Manganese Catalysts for Asymmetric Transfer Hydrogenation of 3-Substituted 2H-1,4-Benzoxazines.

Authors

Chunnian Xia, Nuoqi Jin, Bingyang Wang, Kailin Chen, Li Deng, Lixian Wang, Wei Sun

Published in

The Journal of organic chemistry. Jul 02, 2026. Epub Jul 02, 2026.

Abstract

The efficient synthesis of chiral 3,4-dihydro-2H-1,4-benzoxazines is of considerable interest to both academia and the pharmaceutical industry. Current catalytic methods predominantly rely on precious metals and air-sensitive chiral phosphine ligands. As a cost-effective alternative, the asymmetric reduction of benzoxazine frameworks using earth-abundant metals remains underexplored. Herein, we report manganese catalysts bearing chiral benzimidazole ligands derived from (1S,2S)-1,2-diphenylethylenediamine for the asymmetric transfer hydrogenation (ATH) of 2H-1,4-benzoxazines. This protocol affords chiral 3,4-dihydro-2H-1,4-benzoxazines in excellent yields (up to 99%) with good enantioselectivities (up to 82% ee). The catalytic system retained its enantioselectivity in a gram-scale reaction, underscoring its potential for the practical synthesis of pharmaceutical intermediates containing the 3,4-dihydro-2H-1,4-benzoxazine scaffold.

PMID:
42391642
Bibliographic data and abstract were imported from PubMed on 03 Jul 2026.

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