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Journal ArticleDOI

RuCl2(PPh3)3-catalyzed transfer hydrogenation of d-glucose

15 Sep 1992-Journal of Molecular Catalysis (Elsevier)-Vol. 75, Iss: 2, pp 199-208
Abstract: Glucose is transfer hydrogenated by propan-2-ol, butan-2-ol, cyclohexanol, benzyl alcohol, 1-phenylethanol, benzhydrol, 2-methoxyethanol and tetrahydrofurfuryl alcohol in the presence of RuCl2(PPh3)3 at 100 °C and atmospheric pressure. Mixed solvent systems such as dimethylacetamide-water and dioxane-water are utilized for this reaction. The major product from glucose is sorbitol, although glucono-1,5-lactone is invariably formed as a side product from a disproportionation reaction. When 2-methoxyethanol and tetrahydrofurfuryl alcohol are used as hydrogen donors, the catalyst undergoes permanent change to a hydridocarbonyl complex, which catalyzes only disproportionation of glucose. Glucose also acts as a good hydrogen donor when hydrogen acceptors such as cyclohexanone are introduced into the reaction system.
Topics: Benzyl alcohol (57%), Cyclohexanol (56%), Disproportionation (55%), Cyclohexanone (54%), Catalysis (53%)
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01 Jan 2015-Green Chemistry
Abstract: Biomass has emerged as a potential alternative feedstock to dwindling fossil fuel reserves. Starting in the 1990s, extensive research has been directed towards the synthesis of useful platform chemicals from cellulosic biomass. Chemical conversion processes of biomass have evolved as a parallel approach to thermochemical and enzymatic synthetic routes. In this review, we summarize the recent developments in liquid phase chemical conversions of monosaccharides, disaccharides, and polysaccharides. The reaction processes explored are hydrolysis, oxidation, reduction, hydrogenation, hydrogenolysis, esterification, etherification, glycosylation, dehydration, as well as the functionalization of the polysaccharide backbone. Our review follows a “process-driven” approach where the existing carbohydrate conversion pathways are classified according to the types of chemical processes involved.

230 citations

Journal ArticleDOI
Abstract: The transition from a petroleum-based infrastructure to an industry which utilises renewable resources is one of the key research challenges of the coming years. Biomass, consisting of inedible plant material that does not compete with our food production, is a suitable renewable feedstock. In recent years, much research has been focused on developing new chemical strategies for the valorisation of different biomass components. In addition to the many heterogeneous and enzymatic approaches, homogenous catalysis has emerged as an important tool for the highly selective transformation of biomass, or biomass derived platform chemicals. This Perspective provides an overview of the most important recent developments in homogeneous catalysis towards the production and transformation of biomass and biomass related model compounds. The chemical valorisation of the main components of lignocellulosic biomass – lignin and (hemi)cellulose is reviewed. In addition, important new catalyst systems for the conversion of triglycerides and fatty acids are presented.

216 citations

Journal ArticleDOI
26 Feb 1999-Organometallics
Abstract: Rhodium and platinum isocyanide complexes RhCl(CO)[CN(CH2)3Si(OC2H5)3]2 (Rh−CNR2), RhCl[CN(CH2)3Si(OC2H5)3]3 (Rh−CNR3), and PtCl2[CN(CH2)3Si(OC2H5)3]2 (Pt−CNR2) were tethered to the silica-supported metal heterogeneous catalysts M−SiO2 (M = Pd, Pt, Ru) to give the TCSM (tethered complex on supported metal) catalysts Rh−CNR2/Pd−SiO2, Rh−CNR3/M−SiO2 (M = Pd, Pt, Ru), and Pt−CNR2/Pd−SiO2. These TCSM catalysts were used to catalyze the hydrogenation of arenes (Rh−CNR2/Pd−SiO2 and Rh−CNR3/M−SiO2) and cyclohexanone (Pt−CNR2/Pd−SiO2) under the mild conditions of 40 °C and 1 atm. They exhibit activities that are higher than those of the separate homogeneous rhodium (or platinum) isocyanide complex, the separate silica-supported metal heterogeneous catalyst, or the rhodium (or platinum) complex catalyst tethered on just SiO2. The activities of the TCSM catalysts are strongly affected by the nature and loading of the supported metal in the catalyst. Among the three silica-supported metal M−SiO2 (M = Pd, Pt, Ru) cat...

58 citations

Journal ArticleDOI
Abstract: Treatment of partially protected or unprotected carbohydrates with the RhH(PPh 3 ) 4 -benzalacetone system leads exclusively to glycono-1,4-lactones by regioselective oxidation and subsequent ring restriction.

38 citations

Journal ArticleDOI
07 May 2013-PLOS ONE
TL;DR: To the authors' knowledge, this is the first asymmetric aldol condensation process achieved with whole-cell DERA catalysis and it simplifies and extends previously developed DERA-catalyzed approaches based on the isolated enzyme.
Abstract: Employing DERA (2-deoxyribose-5-phosphate aldolase), we developed the first whole-cell biotransformation process for production of chiral lactol intermediates useful for synthesis of optically pure super-statins such as rosuvastatin and pitavastatin. Herein, we report the development of a fed-batch, high-density fermentation with Escherichia coli BL21 (DE3) overexpressing the native E. coli deoC gene. High activity of this biomass allows direct utilization of the fermentation broth as a whole-cell DERA biocatalyst. We further show a highly productive bioconversion processes with this biocatalyst for conversion of 2-substituted acetaldehydes to the corresponding lactols. The process is evaluated in detail for conversion of acetyloxy-acetaldehyde with the first insight into the dynamics of reaction intermediates, side products and enzyme activity, allowing optimization of the feeding strategy of the aldehyde substrates for improved productivities, yields and purities. The resulting process for production of ((2S,4R)-4,6-dihydroxytetrahydro-2H-pyran-2-yl)methyl acetate (acetyloxymethylene-lactol) has a volumetric productivity exceeding 40 g L−1 h−1 (up to 50 g L−1 h−1) with >80% yield and >80% chromatographic purity with titers reaching 100 g L−1. Stereochemical selectivity of DERA allows excellent enantiomeric purities (ee >99.9%), which were demonstrated on downstream advanced intermediates. The presented process is highly cost effective and environmentally friendly. To our knowledge, this is the first asymmetric aldol condensation process achieved with whole-cell DERA catalysis and it simplifies and extends previously developed DERA-catalyzed approaches based on the isolated enzyme. Finally, applicability of the presented process is demonstrated by efficient preparation of a key lactol precursor, which fits directly into the lactone pathway to optically pure super-statins.

36 citations

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Journal ArticleDOI
Abstract: The interaction of triphenylphosphine, -arsine and -stibine with hydrated ruthenium trichloride in methanol leads to a variety of complexes such as [RuCl2(PPh3)4], [RuCl2(PPh3)3], [RuCl3(PPh3)2CH3OH], [RuCl3(AsPh3)2CH3OH] and [RuCl2(SbPh3)3]. The corresponding bromo complexes are also described. New mono and dicarbonyl complexes of ruthenium (II) and (III) have also been prepared by the interaction of Ph3P, Ph3As, Ph3Sb, pyridine etc., with a carbonyl-containing solution. Complexes of type cis and trans-[RuCl2(CO)2L2], [RuCl2(CO)L3] and [pyH][RuCl4COpy] are described.

686 citations

Journal ArticleDOI
01 Oct 1974-Chemical Reviews
Abstract: 1. Olefins 2. Acetylenes 3. Carbonyl Compounds 4. Nitriles 5. Imines, Hydroxylamines, Hydrazones 6. Azo Compounds 7. Nitro Compounds B. Hydrogenolysis 1 , Nitriles 2. Halides 3. Allylic and Benzylic Functional Groups 4. Amines C. Structural Selectivity D. Special Synthetic Applications IV. Mechanism V . Summary and Prospects V I , References 567 568 568 569 569 570 570 570 570 570 570 571 571 571 571 571 571 571 571 571 573 574 575 576 580 580

589 citations

Journal ArticleDOI
Abstract: The review deals with the new rapidly developing field of homogeneous catalysis and coordination chemistry, namely with reactions involving hydrogen transfer from organic compounds to transition metal complexes accompanied by the dissociation of a C–H bond and the formation of a metal–hydrogen bond. Particular attention has been devoted to catalytic reactions in which transition metal compounds serve as catalysts of hydrogen transfer and of the reduction of organic compounds by the C–H bonds of other organic molecules. The bibliography includes 177 references.

36 citations

Journal ArticleDOI
Abstract: La decarbonylation de C n aldoses non proteges par un complexe du rhodium donne les correspondants C n -1 alditols

25 citations

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