In(OTf)3-Catalyzed Reorganization/Cycloaddition of Two Imine Units and Subsequently Modular Assembly of Acridinium Photocatalysts

Abstract

Reorganization of unsaturated chemical bonds is one of the most promising strategies to generate architecturally diversified and innovative molecular library. Herein, we disclose a novel reorganization/cycloaddition between two imine units catalyzed by In(OTf)3 Lewis acid, which is sharply distinguished from the well-recognized [4+2] cycloaddition version with Povarov reaction. By means of this unprecedented imine chemistry, a collection of synthetically useful dihydroacridines have been synthesized with high functional group compatibility under concise reaction conditions. Preliminary mechanistic studies unravel that α，β-unsaturated imine likely serves as a pivotal intermediate. Notably, handing products give rise to a series of structurally novel and fine-tuneable acridinium photocatalysts, which offers a heuristic paradigm for synthesizing these ones and is also highlighted by facilitating several encouraging dihydrogen coupling reactions efficiently.