From Esters to Alcohols and Back with Ruthenium and Osmium Catalysts

Spasyuk, Denis; Smith, Samantha A. M.; Gusev, Dmitry G.

doi:10.1002/anie.201108956

Cited by 274 publications

(151 citation statements)

References 24 publications

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“…36 containing a tridentate PNN ligand was treated with KOtBu to afford the unusual dimer 91 ( Figure 5). 37 The catalytic activities of 90 and 91 under H 2 (50 bar) were first tested in the HY of methyl benzoate. The Os dimer 91 was an efficient catalyst, but the reaction was slower than with the corresponding Ru complex 93 ( Figure 5).…”

Section: Hydrogention Of Estersmentioning

confidence: 99%

Recent Advances in Osmium-Catalyzed Hydrogenation and Dehydrogenation Reactions

2015

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CONSPECTUS: A current issue in metal-catalyzed reactions is the search for highly efficient transition-metal complexes affording high productivity and selectivity in a variety of processes. Moreover, there is also a great interest in multitasking catalysts that are able to efficiently promote different organic transformations by careful switching of the reaction parameters, such as temperature, solvent, and cocatalyst. In this context, osmium complexes have shown the ability to catalyze efficiently different types of reactions involving hydrogen, proving at the same time high thermal stability and simple synthesis. In the catalytic reduction of C═X (X = O, N) bonds by both hydrogenation (HY) and transfer hydrogenation (TH) reactions, the most interest has been focused on homogeneous systems based on rhodium, iridium, and in particular ruthenium catalysts, which have proved to catalyze chemo- and stereoselective hydrogenations with remarkable efficiency. By contrast, osmium catalysts have received much less attention because they are considered less active on account of their slower ligand exchange kinetics. Thus, this area remained almost neglected until recent studies refuted these prejudices. The aim of this Account is to highlight the impressive developments achieved over the past few years by our and other groups on the design of new classes of osmium complexes and their applications in homogeneous catalytic reactions involving the hydrogenation of carbon-oxygen and carbon-nitrogen bonds by both HY and TH reactions as well as in alcohol deydrogenation (DHY) reactions. The work described in this Account demonstrates that osmium complexes are emerging as powerful catalysts for asymmetric and non-asymmetric syntheses, showing a remarkably high catalytic activity in HY and TH reactions of ketones, aldehydes, imines, and esters as well in DHY reactions of alcohols. Thus, for instance, the introduction of ligands with an NH function, possibly in combination with a pyridine ring, led to a new family of [OsCl2(PP)(NN)] (NN = diamine, 2-aminomethylpyridine; PP = diphosphine) and pincer [OsCl(CNN)(PP)] (HCNN = 6-aryl-2-aminomethylpyridine, 2-aminomethylbenzo[h]quinoline) complexes, which are outstanding catalysts for (asymmetric) HY and TH of carbonyl compounds and DHY of alcohols with turnover numbers and turnover frequencies up to 10(5) and 10(6) h(-1), respectively. In addition, PNN osmium complexes containing the 2-aminomethylpyridine motif have been found to be among the most active catalysts for HY of esters. These complexes have shown catalytic activities that are comparable and in some cases superior to those reported for analogous ruthenium systems. These results give an idea of the potential of Os complexes for the design of new highly productive and robust catalysts for the synthesis of chiral and nonchiral alcohols and amines as well as ketones from alcohols. Thus, we hope that this report will promote increased interest in the chemistry of these metal complexes, opening novel opportunities for new catalyti...

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Section: Hydrogention Of Estersmentioning

confidence: 99%

Recent Advances in Osmium-Catalyzed Hydrogenation and Dehydrogenation Reactions

2015

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“…11) were prepared by treatment of the MHCl(CO)(AsPh 3 ) 3 (M = Os, Ru) precursors with the ligand PyCH 2 NHC 2 H 4 Pi-Pr 2 [56]. Treatment of these complexes with KOt-Bu afforded the unusual dimers 139 and 141 (Fig.…”

Section: Hydrogenation By Molecular Hydrogen Of Esters To Alcoholsmentioning

confidence: 99%

“…Unfortunately, complexes 26 and 36a resulted unsuitable for the DKR of 1-phenylethanol, since the true catalytic species derived from these precatalysts were deactivated in the presence of lipase Inner-and outer-sphere mechanism for ester hydrogenation catalyzed by complexes 139 or 141 [56]. and acyl donors.…”

Section: Racemization and Deuteration Of Alcohols And Aminesmentioning

confidence: 99%

“…11), respectively, as catalysts for ADC of alcohols (Scheme 118) [56]. It was found that the catalytic activity of 139 was particularly impressive in ethanol and propanol at 78 and 96 • C as conversions of these alcohols to ethyl acetate and propyl propionate.…”

Section: Synthesis Of Esters From Alcoholsmentioning

confidence: 99%

“…Scheme 118. Acceptorless dehydrogenation of alcohols to esters catalyzed by the Ru-and Os-complexes 139 and 140[56].Reaction condi tion s: ref lux (presumab ly 71. 8 °C , the boili ng point of et hano l/e thyl acetat e mixtures).…”

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confidence: 99%

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