Gold(I)-catalysed synthesis of a furan analogue of thiamine pyrophosphate

• Amjid Iqbal,
• El-Habib Sahraoui and
• Finian J. Leeper

Beilstein J. Org. Chem. 2014, 10, 2580–2585, doi:10.3762/bjoc.10.270

• , involving gold(I)-catalysed cyclisation of an alkynyl alcohol to form the furan ring. The furan analogue of thiamine diphosphate (ThDP) was also made and tested for binding to and inhibition of pyruvate decarboxylase (PDC) from Zymomonas mobilis (overexpressed in E. coli with a N-terminal His-tag). It is a

• ; pyruvate decarboxylase; thiamine diphosphate; Introduction The biologically active form of vitamin B1 is thiamine diphosphate (ThDP, 1, Figure 1), which is an essential cofactor and involved in a number of metabolic pathways, including oxidative and non-oxidative decarboxylation of α-keto acids (e.g

• ., pyruvate dehydrogenase, pyruvate decarboxylase), the formation of amino acid precursors (acetohydroxy acid synthase), and ketol transfer between sugars (transketolase) [1]. One common feature of ThDP-dependent enzymes is to catalyse the cleavage and formation of bonds adjacent to the carbon of a carbonyl

Multicomponent reactions in nucleoside chemistry

• Mariola Koszytkowska-Stawińska and
• Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

• reported reaction sequence. Ghosh and Kass synthesized nucleosides 119 from 2,3-dihydrofurane 117, ethyl pyruvate, and the silylated nucleobase 118 (Scheme 49) [126]. This method does not strictly comply with the Ugi’s definition of MCRs because of the sequential addition of the substrates. However, in our

• opinion the method is worth noting since it represents an interesting extension of the Vorbrüggen N-glycosylation process. Thus, the reaction sequence leading to nucleosides 119 was initiated by the titanium(IV) chloride-promoted alkylation of 2,3-dihydrofurane 117 with ethyl pyruvate at −78 °C (1 hour

• min; ii. CuSO4·5H2O, Al2O3, microwave irradiation (90 °C), 3–3.5 min. Reagents and reaction conditions: i. PhI(OAc)2 (3 mol %), microwave irradiation (45 °C), 6–9 min. Reagents and reaction conditions: i. 117, ethyl pyruvate, TiCl4, dichloromethane, −78 °C, 1 h; then 118, −78 °C, 1 h; then 23 °C, 1 h

Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• transferred to a glycan acceptor in a glycoprotein by a sialyltransferase [32][33]. A chemoenzymatic method for its preparation is shown in Scheme 1. It is based on the coupling of Fmoc-glycyl-mannosamine with pyruvate catalized by SA-aldolase to afford the N-protected sialic acid. After reaction with CTP

Diastereoselectivity in the Staudinger reaction of pentafluorosulfanylaldimines and ketimines

• Alexander Penger,
• Cortney N. von Hahmann,
• Alexander S. Filatov and
• John T. Welch

Beilstein J. Org. Chem. 2013, 9, 2675–2680, doi:10.3762/bjoc.9.303

• imine 5 resulted only in decomposition. Excess amine 4 that was present was acylated by benzyloxyacetyl chloride to form the corresponding amide. The utility of the ketene–imine cyclization was not limited to aldimines. The addition of SF5Br to the enol acetate of ethyl pyruvate 9 formed ethyl

The myxocoumarins A and B from Stigmatella aurantiaca strain MYX-030

• Tobias A. M. Gulder,
• Snežana Neff,
• Traugott Schüz,
• Tammo Winkler,
• René Gees and
• Bettina Böhlendorf

Beilstein J. Org. Chem. 2013, 9, 2579–2585, doi:10.3762/bjoc.9.293

• . erecta Pd e21 using isotope-labeling experiments that revealed its precursor molecules to be glucose-derived erythrose-4-phosphate (10) and phosphoenol-pyruvate (11, Scheme 1). Due to the observed scrambling of the expected labeling pattern in 13, its biosynthesis has to proceed via a symmetrical

The regulation and biosynthesis of antimycins

• Ryan F. Seipke and
• Matthew I. Hutchings

Beilstein J. Org. Chem. 2013, 9, 2556–2563, doi:10.3762/bjoc.9.290

• , followed by condensation of 3-aminosalicylate and threonine promoted by C1. The A2 domain activates and loads pyruvate onto T2. Pyruvate is subsequently stereospecifically reduced by the KR domain and condensed with threonine by C2. The PKS, AntD posseses one module composed of the domains KS-AT-ACP-TE

• , pyruvate, and 2E-hexenoyl-CoA to conclusively demonstrate the minimum set of enzymes required for biosynthesis of the antimycin dilactone scaffold in vitro [34]. Antimycin tailoring genes All known antimycin gene clusters contain two tailoring enzymes, AntB and AntO (Figure 2). AntB is a discrete

Biosynthesis of rare hexoses using microorganisms and related enzymes

• Zijie Li,
• Yahui Gao,
• Hideki Nakanishi,
• Xiaodong Gao and
• Li Cai

Beilstein J. Org. Chem. 2013, 9, 2434–2445, doi:10.3762/bjoc.9.281

• reduction of pyruvate by L-lactate dehydrogenase (EC 1.1.1.27) [55]. Alternatively, Itoh et al. discovered that DTEase from Pseudomonas sp. ST-24 was a promising enzyme, which was active not only on D-ketohexoses but also on L-ketohexoses [56]. Therefore, L-tagatose was successfully prepared by immobilized

Activation of cryptic metabolite production through gene disruption: Dimethyl furan-2,4-dicarboxylate produced by Streptomyces sahachiroi

• Dinesh Simkhada,
• Huitu Zhang,
• Shogo Mori,
• Howard Williams and
• Coran M. H. Watanabe

Beilstein J. Org. Chem. 2013, 9, 1768–1773, doi:10.3762/bjoc.9.205

• could be envisioned to form through nucleophilic attack of an epoxide as in the case with monensin and other similar natural products [16]. Alternatively, the biosynthesis might involve the dimerization of pyruvate [17][18][19]. Examination of a draft genome sequence of the S. sahachiroi strain has

• implicated a pyruvate aldolase and methyltransferase containing gene cluster as well as potential polyketide gene clusters containing methyltransferase genes, which will be evaluated in due course through genetic knockout experiments of the ΔaziA2 mutant strain. Disruption of the aziA2 gene gave

Recent progress in the discovery of small molecules for the treatment of amyotrophic lateral sclerosis (ALS)

• Allison S. Limpert,
• Margrith E. Mattmann and
• Nicholas D. P. Cosford

Beilstein J. Org. Chem. 2013, 9, 717–732, doi:10.3762/bjoc.9.82

• mitochondrial function [75], an aberrant phenotype, and neurotoxicity [76]. Dichloroacetate (DCA, 35), a compound which inhibits the pyruvate dehydrogenase enzyme, modulates mitochondrial activity [75]. Miquel et al. [75], treated SOD1 G93A mice with 35 added at 500 mg/L to their drinking water. This treatment

An easily accessible sulfated saccharide mimetic inhibits in vitro human tumor cell adhesion and angiogenesis of vascular endothelial cells

• Grazia Marano,
• Claas Gronewold,
• Martin Frank,
• Anette Merling,
• Christian Kliem,
• Sandra Sauer,
• Manfred Wiessler,
• Eva Frei and
• Reinhard Schwartz-Albiez

Beilstein J. Org. Chem. 2012, 8, 787–803, doi:10.3762/bjoc.8.89

• maintained in Eagle’s minimum essential medium (MEM) with Earle’s salts (Biochrom, Berlin, Germany), 2 mM L-glutamine (PAA, Cölbe, Germany), 1 mM sodium pyruvate (Biochrom, Berlin, Germany), 0.1 mM nonessential amino acids (Biochrom, Berlin, Germany), 1.5 g/L NaHCO3 (Biochrom, Berlin, Germany) and 10% fetal

The volatiles of pathogenic and nonpathogenic mycobacteria and related bacteria

• Thorben Nawrath,
• Georgies F. Mgode,
• Bart Weetjens,
• Stefan H. E. Kaufmann and
• Stefan Schulz

Beilstein J. Org. Chem. 2012, 8, 290–299, doi:10.3762/bjoc.8.31

• following ingredients in 1000 mL of distilled water: asparagine (4 g), MgSO4 (0.5 g), K2PO4 (0.5 g), citric acid (1.83 g), ferric ammonium citrate (0.05 g), D-(+)-glucose monohydrate (4.82 g), and sodium pyruvate (4.82 g). The pH was adjusted to 6.8 and the medium was filter-sterilized by using a 0.22 µm

Natural product biosyntheses in cyanobacteria: A treasure trove of unique enzymes

• Jan-Christoph Kehr,
• Douglas Gatte Picchi and
• Elke Dittmann

Beilstein J. Org. Chem. 2011, 7, 1622–1635, doi:10.3762/bjoc.7.191

• alternative NRPS starter modules [33]. Other cyanobacterial strains achieve diversity of anabaenopeptins by a different mode: Promiscuous A-domains [34]. The anabaenopeptin cluster contains five additional NRPS modules and an uncharacterized protein with similarity to pyruvate carboxyltransferases. The

Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids

• M. Isabel Burguete,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2011, 7, 1347–1359, doi:10.3762/bjoc.7.159

• , enhanced selectivity. Some classical examples are provided by the work of Baiker [38][39]. Thus, initial studies focused on the enantioselective hydrogenation of ethyl pyruvate to (R)-ethyl lactate over cinchonidine (CD) modified Pt/Al2O3. The results obtained showed that a dramatic increase in both

• industrial applications. Hydrogenation of ethyl pyruvate. Hydrogenation of dimethyl itaconate. a) Enantioselective hydrogenation of N-(1-phenylethylidene)aniline in IL–CO2; b) Enantioselective hydrogenation of dimethyl itaconate in SILP–scCO2. Selective hydroformylation with a silica supported Rh catalyst

Anthracene appended pyridinium amide–urea conjugate in selective fluorometric sensing of L-N-acetylvaline salt

• Kumaresh Ghosh,
• Tanmay Sarkar and
• Asoke P. Chattopadhyay

Beilstein J. Org. Chem. 2010, 6, 1211–1218, doi:10.3762/bjoc.6.139

• formation of a hydrogen bond with the guest in solution. On addition of an equivalent amount of tetrabutylammonium salts of acetate and pyruvate to the solution of 1, precipitation occurred. A similar finding was observed in the presence of an equivalent amount of the alanine salt. Figure 2 shows the change

• excited state of anthracene is regulated in different ways. We presume that receptor 1 may follow any equilibrium-binding mode A, B or C with valine, alanine and phenylglycine salts in solution as shown in Figure 5. This is also true for the mandelate, pyruvate and proline salts. Relevance of the

• less when compared to all the other guests. Pyruvate with carbonyl at the α-position did not produce any marked change in emission of 1. We also determined the binding constants for 2 with the same anions in CH3CN by fluorescence (Table 2) and the values were found to be less compared to the values for

Asymmetric reactions in continuous flow

• Xiao Yin Mak,
• Paola Laurino and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19

• alternative reaction medium to traditional organic solvents is attractive not only for environmental reasons, but also because of its high miscibility with gases, and its ease of removal from the product (simply by depressurization) [46]. In an early example of asymmetric hydrogenation in flow, ethyl pyruvate

The first organocatalytic carbonyl- ene reaction: isomerisation- free C-C bond formations catalysed by H-bonding thio- ureas

• Matthew L. Clarke,
• Charlotte E. S. Jones and
• Marcia B. France

Beilstein J. Org. Chem. 2007, 3, No. 24, doi:10.1186/1860-5397-3-24

• include ketone enophiles is a highly desired process that can potentially deliver enantio-enriched tertiary alcohols. The most promising results in this regard come from Evans and co-workers who demonstrated that 1,1-disubstituted alkenes would react with the activated ethyl pyruvate to give the desired