Ru–g-C3N4 as a highly active heterogeneous catalyst for transfer hydrogenation of α-keto amide into β-aminol or α-hydroxyl amide

Abstract

This work reports a sustainable route for the catalytic transfer hydrogenation (CTH) of α-keto amide into β-aminol via an efficient heterogeneous catalyst wherein ruthenium is incorporated on an active graphite sheet of a carbon nitride support (Ru–g-C₃N₄). Other different metals like Ni or Pd were also screened with the same support but none of them showed efficient activity. Although, partial hydrogenation of ketone to alcohol has also been observed based on the optimization of the reaction parameters using all of the above catalysts. The catalyst has been characterized using field emission gun scanning electron microscopy (FEG-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infra-red (IR) spectroscopy and thermogravimetric analysis (TGA). Furthermore, the catalyst has been recycled and further characterized and does not show any significant changes in its reactivity for the CTH process. Ru–g-C₃N₄ as a recyclable heterogenous catalyst has been used for the first time for the CTH of α-keto amide into β-aminol, making the process sustainable because economical and environmentally benign isopropyl alcohol is used as a solvent system. The proposed catalytic system shows a wide scope of substrates for α-hydroxyamide and β-aminol derivatives, which were confirmed from ¹H and ¹³C-NMR.