RuCl2(PPh3)3-catalyzed transfer hydrogenation of d-glucose
TL;DR: In this paper, a mixed solvent system such as dimethylacetamide-water and dioxane-water is used for the transfer hydrogenation of glucose to a mixture of mixed solvent systems.
About: This article is published in Journal of Molecular Catalysis.The article was published on 1992-09-15. It has received 16 citations till now. The article focuses on the topics: Benzyl alcohol & Cyclohexanol.
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TL;DR: A review of the recent developments in liquid phase chemical conversions of monosaccharides, disaccharide, and polysaccharides can be found in this paper, followed by a process-driven approach where the existing carbohydrate conversion pathways are classified according to the types of chemical processes involved.
271 citations
TL;DR: In this article, the authors provide an overview of the most important recent developments in homogeneous catalysis towards the production and transformation of biomass and biomass related model compounds, including the chemical valorisation of the main components of lignocellulosic biomass.
244 citations
TL;DR: In this paper, the TCSM (tethered complex on supported metal) catalysts were used to catalyze the hydrogenation of arenes (Rh−CNR2/Pd−SiO2 and rhCl[CN(CH2)3Si(OC2H5)3]2) under mild conditions of 40 °C and 1 atm.
59 citations
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.
39 citations
TL;DR: In this article, the authors show that the 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.
39 citations
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TL;DR: The simple LCAO-MO method of inductive parameters, in the form derived by Del Re, has been applied to the calculation of the electronic structure of some pentoses and the calculated data have been used for the interpretation of some chemical properties of pentoses.
25 citations
TL;DR: In this article, a mixture of glucose and fructose was found to undergo quantitative transfer hydrogenation yielding equal amounts of gluconic acid and of hexitols (mannitol and sorbitol).
Abstract: Equimolar mixtures of glucose and fructose were found to undergo quantitative transfer hydrogenation yielding equal amounts of gluconic acid and of hexitols (mannitol and sorbitol). The oxidationreduction occurs in aqueous alkaline medium under nitrogen at room temperature in the presence of Pt/C or Rh/C as the catalyst. Other group VIII metals did not give satisfactory results. Both a stirred batch and a continuous flow column reactor have been applied. The influence of several reaction variables has been studied, leading to the conclusion that the rate-limiting step ist the dehydrogenation reaction of glucose into gluconic acid and chemisorbed hydrogen. Subsequently, the latter is quickly consumed by coadsorbed fructose under formation of mannitol and sorbitol (in the ratio of 1.5. – 1.9: 1). Alkaline degradation products are found to be of minor importance at temperatures ≦ 25°C.
Katalytische Wasserstoffubertragung in Glucose-Fructosesirupen in alkalischer Losung. Es wurde festgestellt, das aquimolekulare Mischungen von Glucose und Fructose einer quantitativen Wasserstoffubertragung unterliegen, die zu gleichen Mengen Gluconsaure und Hexitolen (Mannitol und Sorbitol) fuhren. Die Oxidation-Reduktion tritt in wasrigem alkalischem Medium unter Stickstoffatmosphare bei Raumtemperatur in Gegenwart von Pt/C oder Rh/C als Katalysatoren auf. Andere Metalle der VIII. Gruppe fuhrten nicht zu befriedigenden Ergebnissen. Fur die Versuche wurden sowohl ein Batch-Reaktor mit Ruhreinrichtung als auch ein kontinuierlicher Durchflus-Saulenreaktor angewendet. Der Einflus verschiedener Reaktionsparameter wurde untersucht, was zu der Schlusfolgerung fuhrte, das der geschwindigkeitsbestimmende Schritt die Dehydrierungsreaktion der Glucose zu Gluconsaure und chemisorbiertem Wasserstoff ist. Anschliesend wird letzterer durch mitadsorbierte Fructose unter Bildung von Mannitol und Sorbitol (Verhaltnis 1, 5 bis 1, 9 zu 1) rasch verbraucht. Die alkalischen Abbauprodukte waren bei Temperaturen ≦ 25°C nur von geringer Bedeutung.
19 citations
17 citations
TL;DR: In this paper, a reaction of transfert catalytique d'hydrogene etudiee avec le di- O -isopropylidene-2,3,4;5-D-mannofuranose comme donneur and RuH 2 (PPh 3 ) 4 comme catalyseur is described.
15 citations
TL;DR: In this article, the aldehydo-glucose was shown to be the main source of carbon monoxide in dimethylacetamide (DMA) and cis-RuCl2(CO)2(PPh3)2.
8 citations