Efficient Synthesis of Quinolines Through Acceptorless Dehydrogenative Coupling Enabled by an Air‐Stable Iridium(III) Pyrazolato Catalyst

Abstract

Quinoline derivatives were synthesized efficiently through acceptorless dehydrogenative coupling of amino alcohols or amino ketones with secondary alcohols using an air‐stable iridium(III) pyrazolato complex as catalyst. The protocol can operate under solvent‐free condition with catalyst loadings as low as 0.3 mol%, providing a broad range of quinoline frameworks in good to excellent yields. The methodology exhibits excellent functional‐group tolerance and utilizes readily accessible substrates, offering a practical route to structurally diverse quinoline derivatives. Importantly, water and molecular hydrogen are generated as the only byproducts, highlighting the sustainability and atom economy of the transformation. Mechanistic studies are consistent with a homogeneous, non‐radical pathway involving alcohol dehydrogenation as a key step, likely assisted by metal–ligand cooperation. The high catalytic efficiency, broad substrate scope and environmentally benign nature of this protocol make it an attractive strategy for the synthesis of valuable quinoline‐based heterocycles.