https://www.sciencedirect.com/science/article/pii/S2589004220301875

Hydrogen Transfer-Mediated Multicomponent Annulation Reaction for Direct Synthesis of Quinazolines by a Naphthyridine-based Iridium Catalyst  

Zhenda Tan¹, Zhongxin Fu², Jian Yang¹, Yang Wu¹, Liang Cao¹, Huanfeng Jiang¹, Juan Li^2,* and Min Zhang^1,3,*

ABSTRACT:Selective linkage of renewable alcohols and ammonia into functional products would not only eliminate pre-preparation steps to generate active amino agents, but also help to the conservation of our finite fossil carbon resources and contributes to reduce CO₂ emission. Herein, reported is the development of a novel 2-(4-methoxyphenyl)-1,8-naphthyridine-based iridium (III) complex, which exhibits excellent catalytic performance toward a new hydrogen transfer-mediated annulation reaction of 2-nitrobenzylic alcohols with alcohols and ammonia. The catalytic transformation proceeds with the striking features of good substrate and functional group compatibility, high step and atom efficiency, no need for additional reductants, and liberation of H₂O as the sole by-product, which endows a new platform for direct access to valuable quinazolines. Mechanistic investigations suggest that the non-coordinated N-atom in the ligand serves as a side arm to significantly promote the condensation process by hydrogen bonding. The work presented paves the avenues for further development of hydrogen transfer-mediated coupling reactions by design of catalysts bearing N-side arm ligands.