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

Abstract

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.

Ru(II)-Catalyzed N-Methylation of Amines Using Methanol as the C1 Source

“…1b−1d were prepared as previously described. 35,36 The 1 H and 13 C NMR spectra were recorded on a Bruker Avance 400 spectrometer.…”

Visible-Light-Promoted Hydrogenation of Azobenzenes to Hydrazobenzenes with Thioacetic Acid as the Reductant

“…In this respect, the combination of an appropriate catalyst and nonmetallic reducing reagents such as hydrazine hydrate (N 2 H 4 ·H 2 O) and boranes (NH 3 ·BH 3 , B 2 pin 2 , and HBpin) was widely explored (Scheme B). More recently, the transition-metal-catalyzed hydrogenation of azobenzenes under Pd/C, Mn­(I), and Ru­(II) was reported by the Balaraman, Rueping, and Xu groups . However, the chemoselectivity for such a process should be difficult to control if other reducible groups are contained …”

In-depth experimental and theoretical investigations on Co-SAC catalyzed transfer hydrogenation of azo compounds using methanol and ethanol

“…30,42,43 During preparation of this manuscript, Xu and coworkers demonstrated protocol for transfer hydrogenation azoarenes using ethanol, catalyzed by a (NC)Ru(II)-complex; however, this catalytic system was incapable for complete hydrogenation of -N=N-bond, produced the hydroazoarenes as the major product. 44 Nowadays, 3d-metal-based single atomic catalysts (SAC) are becoming a promising candidate for developing more efficient catalytic systems for various organic transformations because of their improved atom-utilization efficiency. [45][46][47][48][49][50][51][52] Moreover, the unique electronic structure of the single metal centre on the surface and labile coordination environment around the active site play a vital role in its unique catalytic activity compared to their nanoparticle or nanocluster counterparts.…”