Fast Transfer Hydrogenation(TH) in Aerobic Condition and Oxidation of Alcohols with N‐Methylmorpholine‐N‐oxide Catalyzed by Ru(II) Ligated with Chalcogenated Pyridines and PPh3

Abstract

AbstractThe transfer hydrogenation (TH) of aldehydes / ketones (at mmol level), using propan‐2‐ol as a H‐source is complete within 15 min when catalyzed by 0.1 mol% of [Ru(L)(PPh3)Cl2]] (1–4; L=L1–L4; L1/L2=(E)‐2‐(phenylthio/seleno)‐N‐(pyridin‐2‐ylmethyene)ethan‐amine, L3/L4=2‐(phenylthio/seleno)‐N‐(pyridin‐2‐ylmethyl)ethan‐ amine). The 1–4 were prepared by treating [Ru(PPh3)3Cl2] with L1–L4 respectively.The L1–L4 and 1–4 were characterized by 1H, 13C{1H} and 77Se{1H} NMR spectra. Single crystal structures of 1–4 determined by X‐ray diffraction revealed distorted octahedral geometry of Ru in each complex and bond lengths (Å) as: Ru−S, 2.3441(1) and 2.335(3) and Ru−Se, 2.4497(2) and 2.4518(4). Each of 1–4 (0.1 mol%) is almost equally efficient as catalyst for TH and oxidation of alcohols with N‐methylmorpholine‐N‐oxide (NMO). The optimum amount of oxidant NMO was found 3 mmol for 1 mmol of alcohol. In ambient conditions both the catalytic reactions by the four complexes appear to be homogeneous. The scope of substrates for both the reactions is reported.