Catalytic Deoxygenation of Sulfoxides by Molecular Hydrogen and its Application to the Homologation of Aromatic Aldehydes

Efficient Chemoselective Reduction of N‐Oxides and Sulfoxides Using a Carbon‐Supported Molybdenum‐Dioxo Catalyst and Alcohol

“…While stirring at 500 rpm, the flask was lowered into an oil bath at 120 °C and heated for 3 h. Samples were collected and analyzed via NMR spectroscopy to monitor the course of the reaction. Pyridine N ‐oxide deoxygenation by H 2 produced from direct alcohol oxidation was ruled out because no deoxygenated product was observed under 50 psi of H 2 without alcohol addition …”

Hydrogenation of Sulfoxides to Sulfides under Mild Conditions Using Ruthenium Nanoparticle Catalysts

“…For example, after a 50 mmol-scale reaction of 1, the product 2 was readily isolated in 96 % yield by simple filtration of the catalyst followed by evaporation of the filtrate (Table 2, entry 2). During the hydrogenation reaction, a turnover number as high as 500 was achieved, a value which is significantly larger than those obtained with previously reported catalyst systems requiring high H 2 [b] Yield of 2 [%] [b] pressure (Pd/C: TON 50; [4] MoOCl 2 : TON 50 [15] ). In addition, inductively coupled plasma (ICP) analysis of the filtrate showed no leaching of the Ru species into the reaction mixture, demonstrating the high durability of the Ru/TiO 2 .…”

“…[3] Deoxygenation is also useful in the one-carbon homologation reaction of carbonyl compounds using active a-methylene sulfoxides as carbon sources. [4] The stoichiometric deoxygenation of sulfoxides has typically been carried out with excess amounts of sacrificial agents such as metal hydrides, [5] gaseous halogens, [6] hydrogen halides, [7] thiols, [8] and phosphines.…”

“…However, in early research on the hydrogenation of sulfoxides, the use of RhCl 3 for the hydrogenation of dimethyl sulfoxide (DMSO) resulted in low yields of dimethyl sulfide in the order of 0.4 % together with low catalytic activity (turnover numbers of 2) and an evidently limited range of applicable substrates. [14] Pd/C [4] and MoO 2 Cl 2 [15] exhibited moderate catalytic activities for several sulfoxides but required harsh reaction conditions including high H 2 pressure (> 50 atm). These severe conditions also preclude the use of these catalysts for the selective hydrogenation of functionalized sulfoxides containing other reducible or thermally labile functional groups.…”

“…pressure (Pd/C: TON 50; [4] MoOCl 2 : TON 50 [15] ). In addition, inductively coupled plasma (ICP) analysis of the filtrate showed no leaching of the Ru species into the reaction mixture, demonstrating the high durability of the Ru/TiO 2 .…”