Akademik Veri Yönetim Sistemi
Turkish Journal of Chemistry, cilt.47, sa.5, ss.1209-1223, 2023 (SCI-Expanded)
A low temperature hydrogen borrowing approach to generate secondary amines using benzimidazole-based N-heterocyclic carbene (BNHC) ruthenium complexes is reported. A series of the piano-stool complexes of the type $[(η^6-p-cymene)(BNHC)RuCl_2]$ (1a–g) were synthesized via one-pot reaction of the NHC salt precursor, $$Ag_2O, and [RuCl_2(p-cymene)]_2$ and characterized using con- ventional spectroscopic techniques. The geometry of two precursors, $[( η^6-p-cymene)(^{Me4Bn}Me2BNHC^{CH2OxMe})RuCl2]$ ( 1f) and $[( η^6-p- cymene)(^{Me5Bn}Me_2BNHC^{CH2OxMe})RuCl_2]$ (1g), was studied by single crystal X-ray diffraction. These catalysts were found to dehydrogenate alcohols efficiently at temperatures as low as 50 °C to allow Schiff-base condensation and subsequent imine hydrogenation to afford secondary amines. Notably, this ruthenium-based procedure enables the N-alkylation of aromatic and heteroaromatic primary amines with a wide range of primary alcohols in excellent yields of up to 98%. The present methodology is green and water is liberated as the sole byproduct.