Acceptorless Dehydrogenative Cyclization of o-Aminobenzylamines and Aldehydes to Quinazolines in Water Catalyzed by a Water-Soluble Metal-Ligand Bifunctional Catalyst

摘要

The construction of quinazolines via acceptorless dehydrogenative cyclization of o-aminobenzylamines and aldehydes in water has been accomplished. In the presence of a watersoluble metal-ligand bifunctional catalyst [Cp*Ir(6, 6’-(OH)2 bpy)(H2O)][OTf]2 (2 mol %), reactions were carried out at 130℃ for 12 h in water to afford the desired products in 52–83% yields. Apparently, OH units in the bpy ligand are crucially important for the enhancement of the catalytic activity. The liberation of hydrogen gas in the process of the cyclization was also confirmed. The protocol is highly attractive because of high atom efficiency and environmental friendliness. Notably, this research would facilitate the progress of acceptorless dehydrogenative reactions in water.