Bidentate Ru(II)-NC Complex as a Catalyst for Semihydrogenation of Azoarenes to Hydrazoarenes with Ethanol

The transfer hydrogenation of azoarenes to hydrazoarenes using ethanol as a hydrogen source by a bidentate Ru(II)-NC complex is developed. A weak base is crucial for this semihydrogenation that can efficiently avoid hydrazoarene dehydrogenation under strongly basic conditions. Control experiments and density functional theory calculations demonstrate the mechanism via a Meerwein-Ponndorf-Verley mechanism, and the only byproduct is ethyl acetate. This study offers a new and simple approach for the synthesis of hydrazoarenes.

Automated summary

A new method for the synthesis of hydrazoarenes is developed by using ethanol as a hydrogen source and a bidentate Ru(II)-NC complex as the catalyst. The presence of a weak base is crucial for efficient semihydrogenation, which prevents hydrazoarene dehydrogenation under strongly basic conditions. Control experiments and density functional theory calculations confirm the mechanism as Meerwein-Ponndorf-Verley mechanism, with ethyl acetate as the only byproduct. This study offers a new and simple approach for the synthesis of hydrazoarenes.