53584-56-8

Upstream product

• 58-86-6 D-xylose 
• 1029272-42-1 (2R,3S)-2,3-butanediol 
• 6982-25-8 d,l-2,3-butanediol 
• 849585-22-4 LACTIC ACID 
• 57-48-7 fructose 
• 50-99-7 D-glucose 
• 50-99-7 glucose 
• 75-07-0 acetaldehyde 
• 328-42-7 Oxalacetic acid 
• 127-17-3 2-oxo-propionic acid 
• 431-03-8 dimethylglyoxal 
• 77-92-9 citric acid 
• 57-50-1 Sucrose 
• 71-36-3 butan-1-ol 

Downstream Products

• 99441-04-0 3-O-MTPA-2-butanone 
• 24347-58-8 (R,R)-2,3-butandiol 
• 171194-77-7 (R)-3-oxobutan-2-yl benzoate 

Relevant academic research and scientific papers

α-Hydroxy-β-keto acid rearrangement-decarboxylation: Impact on thiamine diphosphate-dependent enzymatic transformations

The thiamine diphosphate (ThDP) dependent MenD catalyzes the reaction of α-ketoglutarate with pyruvate to selectively form 4-hydroxy-5-oxohexanoic acid 2, which seems to be inconsistent with the assumed acyl donor role of the physiological substrate α-KG. In contrast the reaction of α-ketoglutarate with acetaldehyde gives exclusively the expected 5-hydroxy-4-oxo regioisomer 1. These reactions were studied by NMR and CD spectroscopy, which revealed that with pyruvate the observed regioselectivity is due to the rearrangement-decarboxylation of the initially formed α-hydroxy-β-keto acid rather than a donor-acceptor substrate role variation. Further experiments with other ThDP-dependent enzymes, YerE, SucA, and CDH, verified that this degenerate decarboxylation can be linked to the reduced enantioselectivity of acyloins often observed in ThDP-dependent enzymatic transformations.

Studies on structure-function relationships of acetolactate decarboxylase from: Enterobacter cloacae

Acetoin is an important bio-based platform chemical with wide applications. Among all bacterial strains, Enterobacter cloacae is a well-known acetoin producer via α-acetolactate decarboxylase (ALDC), which converts α-acetolactate into acetoin and is identified as the key enzyme in the biosynthetic pathway of acetoin. In this work, the enzyme properties of Enterobacter cloacae ALDC (E.c.-ALDC) were characterized, revealing a Km value of 12.19 mM and a kcat value of 0.96 s-1. Meanwhile, the optimum pH of E.c.-ALDC was 6.5, and the activity of E.c.-ALDC was activated by Mn2+, Ba2+, Mg2+, Zn2+ and Ca2+, while Cu2+ and Fe2+ significantly inhibited ALDC activity. More importantly, we solved and reported the first crystal structure of E.c.-ALDC at 2.4 ? resolution. The active centre consists of a zinc ion coordinated by highly conserved histidines (199, 201 and 212) and glutamates (70 and 259). However, the conserved Arg150 in E.c.-ALDC orients away from the zinc ion in the active centre of the molecule, losing contact with the zinc ion. Molecular docking of the two enantiomers of α-acetolactate, (R)-acetolactate and (S)-acetolactate allows us to further investigate the interaction networks of E.c.-ALDC with the unique conformation of Arg150. In the models, no direct contacts are observed between Arg150 and the substrates, which is unlikely to maintain the stabilization function of Arg150 in the catalytic reaction. The structure of E.c.-ALDC provides valuable information about its function, allowing a deeper understanding of the catalytic mechanism of ALDCs.

An artificial enzymatic reaction cascade for a cell-free bio-system based on glycerol

Conversion of glycerol into high-value products is of significant importance for sustainability in the biofuel industry. In this study, pyruvic acid, a central intermediate needed for the production of versatile biomolecules, was produced from glycerol without the addition of any cofactors by the cell-free bio-system composed of alditol oxidase, dihydroxy acid dehydratase, and catalase. (3R)-Acetoin was then produced at 85.5% of the theoretical yield from glycerol by α-acetolactate synthase and α-acetolactate decarboxylase. Since other biomolecules can also be produced from pyruvic acid, the cell-free bio-system might serve as a versatile bio-production platform, and support the viability of the biofuel economy. This journal is

Enantioselective enzymatic synthesis of the α-hydroxy ketone (R)-acetoin from meso-2,3-butanediol

Acetoin (3-hydroxy-2-butanone) is an important flavour compound and is applied in cosmetics, pharmacy and chemical synthesis. In contrast to chemical syntheses or fermentations an enzymatic route facilitates enantioselective acetoin production. The discovery of a (S)-selective alcohol dehydrogenase enables a novel production process of (R)-acetoin from meso-2,3-butanediol. It was shown that the regeneration of oxidised nicotinamide adenine dinucleotide is a key point in preparative application of dehydrogenases for the oxidative route. An electrochemical regeneration system was successful combined with the ADH catalysed reaction. Up to 48 mM (R)-acetoin was produced in the reaction system while productivities up to 2 mM h-1 were reached. The possibility to apply an electrochemical system in a semi-preparative synthesis will stimulate further research of electroenzymatic processes with oxidoreductases.

Enantioselective hydrogenation of activated ketones in the presence of Pt-cinchona catalysts. Is the proton transfer concept valid?

Experimental evidences related to the proton transfer in the catalytic system Pt-cinchona alkaloids for enantioselective hydrogenation of activated ketones were collected and analyzed. Both new and earlier results indicate that in aprotic media direct transfer of proton from platinum to the substrate with the involvement of quinuclidine nitrogen as a general rule can be questioned.

Biocatalytic production of alpha-hydroxy ketones and vicinal diols by yeast and human aldo-keto reductases

The α-hydroxy ketones are used as building blocks for compounds of pharmaceutical interest (such as antidepressants, HIV-protease inhibitors and antitumorals). They can be obtained by the action of enzymes or whole cells on selected substrates, such as diketones. We have studied the enantiospecificities of several fungal (AKR3C1, AKR5F and AKR5G) and human (AKR1B1 and AKR1B10) aldo-keto reductases in the production of α-hydroxy ketones and diols from vicinal diketones. The reactions have been carried out with pure enzymes and with an NADPH-regenerating system consisting of glucose-6-phosphate and glucose-6-phosphate dehydrogenase. To ascertain the regio and stereoselectivity of the reduction reactions catalyzed by the AKRs, we have separated and characterized the reaction products by means of a gas chromatograph equipped with a chiral column and coupled to a mass spectrometer as a detector. According to the regioselectivity and stereoselectivity, the AKRs studied can be divided in two groups: one of them showed preference for the reduction of the proximal keto group, resulting in the S-enantiomer of the corresponding α-hydroxy ketones. The other group favored the reduction of the distal keto group and yielded the corresponding R-enantiomer. Three of the AKRs used (AKR1B1, AKR1B10 and AKR3C1) could produce 2,3-butanediol from acetoin. We have explored the structure/function relationships in the reactivity between several yeast and human AKRs and various diketones and acetoin. In addition, we have demonstrated the utility of these AKRs in the synthesis of selected α-hydroxy ketones and diols.

Silica supported rhodium metal nanoparticles stabilized with (-)-DIOP. Effect of ligand concentration and metal loading on the enantioselective hydrogenation of ketones

Supported nanoparticles (NPs) in presence of chiral ligand (L) were synthesized for their use in enantioselective hydrogenation reactions. Catalysts were obtained by chemical reduction from rhodium chloride hydrate, RhCl 3×3H2O, in presence of (-)-DIOP ligand ((4R,5R)-4,5-Bis(diphenylphosphino-methyl)- 2,2-dimethyl-1,3-dioxolane) that allows to control NPs growing and to obtain solids having chiral surfaces. Chirally stabilized rhodium NPs on SiO2 were characterized using techniques such as: TEM, electron diffraction, EDS, nitrogen adsorption-desorption isotherms and XPS. This work includes the study of some variables such as metal loading and ligand concentration and their effect in metal core sizes, catalytic activity and enantioselectivity. Catalysts properties have also been evaluated in the hydrogenation of substrates: acetophenone (AP), 1-phenyl-1,2-propanedione (PPD), 3,4-hexanedione (HD), 2,3-butanedione (BD) and ethyl pyruvate (EP) as reaction test. Ligand plays a fundamental role in the synthesis of NPs and enantioselectivity in hydrogenations reactions. That is, due to it generates metal particle size 5.8 nm compared with unstabilized systems that generate average diameter around 14 nm. Results indicate increased activity in catalytic systems obtained from the stabilization of NPs. Enantioselectivity levels reach values up to 53% due to the chiral ligand is on the catalysts surface.

Chemoselective aerobic diol oxidation by palladium(II)-pyridine catalysis

Neutral and cationic palladium complexes that bear pyridine ligands [i.e., pyridine (Py), 4-ethylpyridine (4-EtPy) and 2,4,6-trimethylpyridine (2,4,6-Me3Py)] have been isolated and characterized in solution by 1H and 13C{1H} NMR spectroscopy, cyclic voltammetry (CV) and in the solid state by elemental analysis and single-crystal structure analysis. All palladium compounds have been scrutinized as a precursor to catalyze the aerobic oxidation of diols either in the presence or in the absence of an external base (i.e., K2CO3). As a result, the chemoselective production of the corresponding hydroxy ketones has been achieved. The bis-cationic palladium complex of the formula [Pd(4-EtPy)4](OTs)2 (OTs = p-toluenesulfonate) [5b(OTs)2] emerged as the most promising precursor; it outperformed the neutral precursor that consisted of trans-[Pd(OAc)2(4-EtPy) 2] (OAc = acetate) and 4-EtPy [3b/2(4-EtPy)] (2 mol-equiv.). An operando high-pressure (HPNMR) spectroscopic study with the precursor 5b(OTs)2 combined with the results obtained from catalytic reactions has provided insight into the catalytic mechanism that is operative in 5b(OTs)2-catalyzed aerobic diol oxidation reactions. Neutral and cationic palladium(II) complexes with pyridine ligands were synthesized and employed as catalyst precursors for the aerobic K2CO 3-assisted oxidation of unprotected diols to chemoselectivelygive hydroxy ketones. Within the series of catalyst precursors studied, the bis-cationic compound [Pd(4-EtPy)4](OTs)2 (Py = pyridine, OTs = p-toluenesulfonate) emerged as the most promising.

The enzymatic asymmetric conjugate umpolung reaction

The Stetter reaction employs synthetically useful umpolung reactivity to provide catalytic access to 1,4-bifunctional molecules. The first enzymatic 1,4-addition is described, with the ThDP-dependent enzyme PigD, which makes the challenging asymmetric int

Biocatalytic racemization of synthetically important functionalized α-hydroxyketones using microbial cells

Biocatalytic racemization of straight-chain and cyclic acyloins bearing (halo)alkyl, alkenyl and functionalized (hetero)aryl moieties was accomplished using whole resting cells of bacteria, fungi and yeasts. Mild physiological reaction conditions ensured the suppression of undesired side-reactions, such as elimination or condensation. This biocatalytic protocol represents a useful tool for the clean racemization of unwanted enantiomers of synthetically important α-hydroxyketones derived from kinetic resolution.