Selective oxidation of C (sp3)—H bonds enabled by ruthenium clusters containing pyridine‐alkoxide ligands

Abstract

Reactions of Ru3(CO)12 with 6‐methyl‐2‐pyridinyl‐ethanol ligands 6‐CH3‐2‐PyCH2CR1R2OH [R1H, R22‐CH3OC6H4 (L1H); R1H, R22‐CF3C6H4 (L2H); R1R2CH3 (L3H); and R1H, R22,6‐(CH3O)2C6H3 (L4H)] in refluxing THF afforded the corresponding trinuclear ruthenium clusters (6‐CH3‐2‐PyCH2CR1R2O)(μ2‐H)Ru3(CO)9 [R1H, R22‐CH3OC6H4 (1); R1H, R22‐CF3C6H4 (2); R1R2CH3 (3); and R1H, R22,6‐(CH3O)2C6H3 (4)], respectively. All the four new clusters were well characterized by elemental analysis, IR, 1H, and 13C nuclear magnetic resonance. Furthermore, their crystal structures were determined by single‐crystal X‐ray diffraction analysis. The ruthenium clusters were proved to be efficient catalysts for the oxidation of saturated CH bonds with tert‐butyl hydroperoxide (TBHP) as the oxidant in CH3CN/H2O (1:4) at room temperature.