Arylation de glycals catalysée par les sels de palladium: nouvelle synthèse de C-glycosides

1983 ◽  
Vol 61 (3) ◽  
pp. 533-540 ◽  
Author(s):  
Stanislas Czernecki ◽  
Veronique Dechavanne
Keyword(s):  
Double Bond ◽  
Aromatic Compound ◽  
Aromatic Compounds ◽  
Aromatic Nucleus ◽  
Title Reaction ◽  
New Synthesis ◽  
Nitro Derivatives ◽  
Step Mechanism

The arylation of peracetylated glycals catalyzed by palladium salts provides a new synthesis of C-glycosides. The title reaction is applied to several aromatic compounds, including fluoro and nitro derivatives. The regioselectivity of the reaction with respect to the aromatic nucleus is explained by the formation of an arylpalladium directly from the aromatic compound and the salt. A two-step mechanism, involving syn-addition of the arylpalladium to the glycal double bond, followed by a syn-elimination is proposed and discussed.

scholarly journals Chromosome Engineering To Generate Plasmid-Free Phenylalanine- and Tyrosine-Overproducing Escherichia coli Strains That Can Be Applied in the Generation of Aromatic-Compound-Producing Bacteria

2020 ◽  
Vol 86 (14) ◽  
Author(s):  
Daisuke Koma ◽  
Takahiro Kishida ◽  
Eisuke Yoshida ◽  
Hiroyuki Ohashi ◽  
Hayato Yamanaka ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Aromatic Compound ◽  
Aromatic Compounds ◽  
High Yield ◽  
Rational Approach ◽  
Chromosome Engineering ◽  
Phenyllactic Acid ◽  
Content Type ◽  
E Coli ◽  
Free Strains

ABSTRACT Many phenylalanine- and tyrosine-producing strains have used plasmid-based overexpression of pathway genes. The resulting strains achieved high titers and yields of phenylalanine and tyrosine. Chromosomally engineered, plasmid-free producers have shown lower titers and yields than plasmid-based strains, but the former are advantageous in terms of cultivation cost and public health/environmental risk. Therefore, we engineered here the Escherichia coli chromosome to create superior phenylalanine- and tyrosine-overproducing strains that did not depend on plasmid-based expression. Integration into the E. coli chromosome of two central metabolic pathway genes (ppsA and tktA) and eight shikimate pathway genes (aroA, aroB, aroC, aroD, aroE, aroGfbr, aroL, and pheAfbr), controlled by the T7lac promoter, resulted in excellent titers and yields of phenylalanine; the superscript “fbr” indicates that the enzyme encoded by the gene was feedback resistant. The generated strain could be changed to be a superior tyrosine-producing strain by replacing pheAfbr with tyrAfbr. A rational approach revealed that integration of seven genes (ppsA, tktA, aroA, aroB, aroC, aroGfbr, and pheAfbr) was necessary as the minimum gene set for high-yield phenylalanine production in E. coli MG1655 (tyrR, adhE, ldhA, pykF, pflDC, and ascF deletant). The phenylalanine- and tyrosine-producing strains were further applied to generate phenyllactic acid-, 4-hydroxyphenyllactic acid-, tyramine-, and tyrosol-producing strains; yield of these aromatic compounds increased proportionally to the increase in phenylalanine and tyrosine yields. IMPORTANCE Plasmid-free strains for aromatic compound production are desired in the aspect of industrial application. However, the yields of phenylalanine and tyrosine have been considerably lower in plasmid-free strains than in plasmid-based strains. The significance of this research is that we succeeded in generating superior plasmid-free phenylalanine- and tyrosine-producing strains by engineering the E. coli chromosome, which was comparable to that in plasmid-based strains. The generated strains have a potential to generate superior strains for the production of aromatic compounds. Actually, we demonstrated that four kinds of aromatic compounds could be produced from glucose with high yields (e.g., 0.28 g tyrosol/g glucose).

A NEW MUSTARD OIL GLUCOSIDE SYNTHESIS: THE SYNTHESIS OF GLUCOTROPAEOLIN

1963 ◽  
Vol 41 (11) ◽  
pp. 2836-2838 ◽  
Author(s):  
M. H. Benn
Keyword(s):  
Double Bond ◽  
Mustard Oil ◽  
Nitrile Oxides ◽  
New Synthesis ◽  
Nitrogen Double Bond

A new synthesis of mustard oil glucosides is described, illustrated by the synthesis of glucotropaeolin. This synthesis, based on the reaction of thiols with nitrile oxides, leads to a conclusion concerning the stereochemistry about the carbon–nitrogen double bond in the mustard oil glucosides.

scholarly journals Orthoamide, LXIII [1]. Tris(dichlormethyl)amin, ein neues breit anwendbares Formylierungsmittel für Aromaten / Orthoamides, LXIII [1]. Tris(dichloromethyl)amine, a New Formylating Reagent for Aromatic Compounds of Wide Scope

2006 ◽  
Vol 61 (4) ◽  
pp. 448-463 ◽  
Author(s):  
Willi Kantlehner ◽  
Ralf Kreß ◽  
Franziska Zschach ◽  
Jens Vetter ◽  
Georg Ziegler ◽  
...  
Keyword(s):  
Aluminum Chloride ◽  
Aromatic Compounds ◽  
Lewis Acids ◽  
Aluminium Chloride ◽  
Aromatic Nucleus ◽  
Wide Scope ◽  
Formyl Group ◽  
Reaction Conditions ◽  
Optimal Reaction

The reagent system formed from tris(dichloromethyl)amine (5) and aluminium chloride allows the formylation of aromatic compounds. The scope of the method is comparable with that of the Olah formylation and the Groß-Rieche procedure, since benzene and even chlorobenzene can be formylated. One formyl group is transferred from 5 to the aromatic nucleus. In order to find optimal reaction conditions, the molar amounts of aromatic compounds, 5 and aluminum chloride were varied as well as reaction temperatures and solvents. The activation of 5 with other Lewis acids is also described

Metal-Free Addition of Boronic Acids to Silylnitronates

Synlett ◽  
2020 ◽  
Vol 31 (09) ◽  
pp. 856-860
Author(s):  
Laurent El Kaïm ◽  
Mansour Dolé Kerim ◽  
Pakoupati Boyode ◽  
Julian Garrec
Keyword(s):  
Reaction Mechanism ◽  
Double Bond ◽  
Boronic Acids ◽  
Dft Study ◽  
Metal Free ◽  
Nitro Derivatives ◽  
Oxime Derivatives ◽  
Nitrogen Double Bond ◽  
First Time ◽  
Aryl Transfer

We report for the first time a metal-free addition of boronic acids to silylnitronates to afford oxime derivatives through aryl transfer on the carbon nitrogen double bond. A reaction mechanism has been proposed in relation with a DFT study on the key aryl transfer. This arylation process is effective for cycloalkenyl nitro derivatives leading to oximes that may be oxidatively converted into 3-arylisoxazole derivatives.

scholarly journals Hierarchy of Carbon Source Utilization in Soil Bacteria: Hegemonic Preference for Benzoate in Complex Aromatic Compound Mixtures Degraded by Cupriavidus pinatubonensis Strain JMP134

2015 ◽  
Vol 81 (12) ◽  
pp. 3914-3924 ◽  
Author(s):  
Danilo Pérez-Pantoja ◽  
Pablo Leiva-Novoa ◽  
Raúl A. Donoso ◽  
Cedric Little ◽  
Margarita Godoy ◽  
...  
Keyword(s):  
Aromatic Compound ◽  
Aromatic Compounds ◽  
Carbon Sources ◽  
Transcriptional Level ◽  
Catabolic Pathways ◽  
Content Type ◽  
Bacteria Growth ◽  
Reverse Transcription Pcr ◽  
Aromatic Components ◽  
Metabolic Properties

ABSTRACTCupriavidus pinatubonensisJMP134, like many other environmental bacteria, uses a range of aromatic compounds as carbon sources. Previous reports have shown a preference for benzoate when this bacterium grows on binary mixtures composed of this aromatic compound and 4-hydroxybenzoate or phenol. However, this observation has not been extended to other aromatic mixtures resembling a more archetypal context. We carried out a systematic study on the substrate preference ofC. pinatubonensisJMP134 growing on representative aromatic compounds channeled through different catabolic pathways described in aerobic bacteria. Growth tests of nearly the entire set of binary combinations and in mixtures composed of 5 or 6 aromatic components showed that benzoate and phenol were always the preferred and deferred growth substrates, respectively. This pattern was supported by kinetic analyses that showed shorter times to initiate consumption of benzoate in aromatic compound mixtures. Gene expression analysis by real-time reverse transcription-PCR (RT-PCR) showed that, in all mixtures, the repression by benzoate over other catabolic pathways was exerted mainly at the transcriptional level. Additionally, inhibition of benzoate catabolism suggests that its multiple repressive actions are not mediated by a sole mechanism, as suggested by dissimilar requirements of benzoate degradation for effective repression in different aromatic compound mixtures. The hegemonic preference for benzoate over multiple aromatic carbon sources is not explained on the basis of growth rate and/or biomass yield on each single substrate or by obvious chemical or metabolic properties of these aromatic compounds.

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