Efficient ruthenium(II) complex catalyzed N-alkylation of amines and β-alkylation of secondary alcohol via borrowing hydrogen methodology

Abstract

Ruthenium(II) carbonyl complexes with chromone Schiff base ligands of the type [RuCl(CO)(EPh3)(L)] (1–4) (E = P or As, L = 3-(benzothiazol-2-yl-hydrazonomethyl-chromen)-4-one (BTHC) or 3-(quinolin-2-yl-hydrazonomethyl)-chromen-4-one (QHC) were formulated and subjected to micro we well as spectral analysis (IR, UV–Vis, 1H & 13C NMR and ESI mass). The molecular structure of complex 3 was studied by means of single crystal X-ray diffraction analysis. The result shows that the complex possesses a distorted octahedral geometry with the ligand coordinating in a uni-negative tridentate NSO/NNO fashion. The ruthenium complexes (1–4) were screened as catalyst on N-alkylation and β-alkylation reactions. Notably, complex 1 was found to be a very effective and flexible catalyst for N-alkylation of a wide range of primary amines with alcohols. Furthermore, performance of complex 1 as catalyst for β-alkylation of 20 alcohols with 10 alcohols shows promising results with good conversion.