Triruthenium carbonyl complexes containing bidentate pyridine–alkoxide ligands for highly efficient oxidation of primary and secondary alcohols

Abstract

Reactions of substituted pyridylalkanol 6‐CH3PyCH2CH(OH)R (R = Ph (L1H), R = 4‐CH3C6H4 (L2H), R = 4‐OCH3C6H4 (L3H), R = 4‐ClC6H4 (L4H), R = 4‐BrC6H4 (L5H), R = 4‐CF3C6H4 (L6H)) with Ru3(CO)12 in refluxing tetrahydrofuran afforded the corresponding ruthenium carbonyl complexes [6‐CH3PyCH2CHRO]2Ru3(CO)8 (R = Ph (1a), R = 4‐CH3C6H4 (1b), R = 4‐OCH3C6H4 (1c), R = 4‐ClC6H4 (1d), R = 4‐BrC6H4 (1e), R = 4‐CF3C6H4 (1f)) in good yields. These ruthenium complexes were well characterized using elemental analysis and Fourier transform infrared and NMR spectroscopies. Furthermore, their crystal structures were determined using single‐crystal X‐ray diffraction analysis. Complexes 1a–1f were found to be highly active toward oxidation of a wide range of primary and secondary alcohols to corresponding aldehydes and ketones within 5 minutes in the presence of N‐methylmorpholine‐N‐oxide as oxidant.

Direct Deoxygenation of α-Hydroxy and α,β-Dihydroxy Ketones Using a Silyl Lithium Reagent

“…. 27 Isolated yield of 84 mg, 63%, purified by silica gel column chromatography (99:1 petroleum ether/ ethyl acetate), colorless liquid; 1 H NMR (400 MHz, CDCl 3 ) δ 7.77 (d, J = 8.3 Hz, 2 H), 7.17 (d, J = 7.9 Hz, 2 H), 2.49 (s, 3 H), 2.32 (s, 3 H).…”

Synthesis and catalytic activity of tetradentate β-diketiminato rare-earth metal monoalkyl complexes in tandem Oppenauer oxidation and cross-aldol condensation

“…11 From then on, homo-and hetero-catalysts have been widely utilized for this kind of alcohol oxidation. The most widely used catalysts are aluminum alkoxides; [12][13][14] nevertheless, some metal catalysts such as ruthenium, [15][16][17] zirconia, 18 iridium, 19,20 iron complexes [21][22][23] and t-OBuSmI 2 24 have also been employed in Oppenauer-type oxidation. In this reaction, the oxidation of primary alcohols remains much less explored because the products of aldehyde will further react with ketones to give a condensation by-product or cause the Tishchenko reaction to produce dimeric esters.…”