scholarly journals Base-Mediated Generation of Ketenimines from Ynamides: [3+2] Annulation with Azaallyl Anions.

2020 ◽  
Author(s):  
Agathe C. A. D’Hollander ◽  
Eugénie Romero ◽  
Kamsana Vijayakumar ◽  
Camille le Houérou ◽  
Pascal Retailleau ◽  
...  
Keyword(s):  
Dft Calculation ◽  
Reactive Intermediates ◽  
Reaction Conditions ◽  
Stereo Selectivity

Under basic conditions and heat, ynamides can serve as precursor to ketenimines, whose synthetic potential is often hampered by their difficulty of acces. Herein, we report that they can undergo a [3+2] cycloaddition with 2-azaallyl anions, obtained from benzylimines under the same reaction conditions. This reaction between two highly reactive intermediates, both generated in situ from bench stable starting materials, gives access to various nitrogen-rich heterocycles. The reaction usually proceeds with excellent diastereoselectivity, in favor of the cis adduct. Deuteration experiments and DFT calculation helped rationalize the regio and stereo-selectivity of the process as well as the formation of side-products.<br>

scholarly journals Base-Mediated Generation of Ketenimines from Ynamides: [3+2] Annulation with Azaallyl Anions.

2020 ◽  
Author(s):  
Agathe C. A. D’Hollander ◽  
Eugénie Romero ◽  
Kamsana Vijayakumar ◽  
Camille le Houérou ◽  
Pascal Retailleau ◽  
...  
Keyword(s):  
Dft Calculation ◽  
Reactive Intermediates ◽  
Reaction Conditions ◽  
Stereo Selectivity

Under basic conditions and heat, ynamides can serve as precursor to ketenimines, whose synthetic potential is often hampered by their difficulty of acces. Herein, we report that they can undergo a [3+2] cycloaddition with 2-azaallyl anions, obtained from benzylimines under the same reaction conditions. This reaction between two highly reactive intermediates, both generated in situ from bench stable starting materials, gives access to various nitrogen-rich heterocycles. The reaction usually proceeds with excellent diastereoselectivity, in favor of the cis adduct. Deuteration experiments and DFT calculation helped rationalize the regio and stereo-selectivity of the process as well as the formation of side-products.<br>

scholarly journals Synthesis of polysubstituted spiropyrrolidines using 2-acetylfuran, 2-acetylthiophene, and 2-acetylpyrrole

2021 ◽  
Vol 21 (3) ◽  
pp. 254-259
Author(s):  
Svetlana V. Borisova ◽  
◽  
Vitaly V. Sorokin ◽  
Keyword(s):  
13C Nmr Spectroscopy ◽  
Azomethine Ylides ◽  
Dipolar Cycloaddition ◽  
Knoevenagel Reaction ◽  
Atom Economy ◽  
Reaction Conditions ◽  
Stereo Selectivity ◽  
Decarboxylative Condensation ◽  
First Time

A series of novel spirooxindoles have been synthesized through three-component 1,3-dipolar cycloaddition of azomethine ylides generated in situ by the decarboxylative condensation of isatin and sarcosine with the dipolarophile 3-phenyl-1-(heteroaryl -2-yl)prop-2-en-1- one, synthesized by the Knoevenagel reaction using 2-acetylfuran, 2-acetylpyrrole, 2-acetylthiophene and substituted benzaldehydes. These compounds are used for the first time as dipolarophiles. This method has the advantages of mild reaction conditions, high atom economy, excellent yields, and high regio- and stereo-selectivity. The reaction was carried out by mixing equimolar amounts of enone and isatin, as well as a slight excess of sarcosine in isopropyl alcohol when heated to 60–70°C. Among the enones with various heterocyclic substituents, it is most convenient to use compounds containing a pyrrole fragment as dipolarophiles, since the products are obtained in a short amount of time in good yields. The use of enones obtained from 2-acetylthiophene leads to an increase in the reaction time, and from 2-acetylfuran - to a significant resinification of the reaction mixture. The structures of the compounds obtained were proved using a combination of 1H, 13C NMR spectroscopy data, as well as two-dimensional NMR experiments of heteronuclear correlation, HSQC and HMBC. Based on the data obtained, a mechanism for the formation of products has been proposed.

The high enrichment of Geobacter by TiN nanoarray anode catalyst for efficient microbial fuel cells

2021 ◽  
Vol 9 (12) ◽  
pp. 7726-7735
Author(s):  
Da Liu ◽  
Weicheng Huang ◽  
Qinghuan Chang ◽  
Lu Zhang ◽  
Ruiwen Wang ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Hierarchical Structure ◽  
Microbial Fuel Cells ◽  
Dft Calculation ◽  
Experimental Results ◽  
Carbon Cloth ◽  
Anode Catalyst ◽  
High Enrichment

TiN nanoarrays, in situ grown on carbon cloth gather 97.2% of the model exoelectrogen Geobacter, greatly enhancing the MFCs' performance. The experimental results and DFT calculation certify the importance of the micro–nano-hierarchical structure.

scholarly journals One-Pot Synthesis of Novel Multisubstituted 1-Alkoxyindoles

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1466
Author(s):  
Ye Eun Kim ◽  
Hyunsung Cho ◽  
Yoo Jin Lim ◽  
Chorong Kim ◽  
Sang Hyup Lee
Keyword(s):  
Alkyl Halide ◽  
The Novel ◽  
Reaction Conditions ◽  
One Pot ◽  
One Pot Synthesis ◽  
Consecutive Reactions ◽  
Intramolecular Condensation ◽  
Synthetic Sequence ◽  
Novel Target

Studies on a one-pot synthesis of novel multisubstituted 1-alkoxyindoles 1 and their mechanistic investigations are presented. The synthesis of 1 was successfully achieved through consecutive four step reactions from substrates 2. The substrates 2, prepared through a two-step synthetic sequence, underwent three consecutive reactions of nitro reduction, intramolecular condensation, and nucleophilic 1,5-addition to provide the intermediates, 1-hydroxyindoles 8, which then were alkylated in situ with alkyl halide to afford the novel target products 1. We optimized the reaction conditions for 1 focusing on the alkylation step, along with the consideration of formation of intermediates 8. The optimized condition was SnCl2·2H2O (3.3 eq) and alcohols (R1OH, 2.0 eq) for 1–2 h at 40 °C and then, base (10 eq) and alkyl halides (R2Y, 2.0 eq) for 1–4 h at 25–50 °C. Notably, all four step reactions were performed in one-pot to give 1 in good to modest yields. Furthermore, the mechanistic aspects were also discussed regarding the reaction pathways and the formation of side products. The significance lies in development of efficient one-pot reactions and in generation of new 1-alkoxyindoles.

In situ loading of well-dispersed silver nanoparticles on nanocrystalline magnesium oxide for real-time monitoring of catalytic reactions by surface enhanced Raman spectroscopy

Nanoscale ◽  
2015 ◽  
Vol 7 (40) ◽  
pp. 16952-16959 ◽  
Author(s):  
Kaige Zhang ◽  
Gongke Li ◽  
Yuling Hu
Keyword(s):  
Raman Spectroscopy ◽  
Surface Enhanced Raman Spectroscopy ◽  
Catalytic Reactions ◽  
Reaction Intermediates ◽  
Reaction Conditions ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Nanocrystalline Magnesium Oxide ◽  
Insight Into

The surface-enhanced Raman spectroscopy (SERS) technique is of great importance for insight into the transient reaction intermediates and mechanistic pathways involved in heterogeneously catalyzed chemical reactions under actual reaction conditions, especially in water.

Diffuse Reflectance FT-IR Characterization of Active Sites under Reaction Conditions: The Production of Oxygenates in the CO/H2 Reaction

1994 ◽  
Vol 48 (10) ◽  
pp. 1208-1212 ◽  
Author(s):  
J. J. Benítez ◽  
I. Carrizosa ◽  
J. A. Odriozola
Keyword(s):  
Infrared Spectra ◽  
Active Sites ◽  
Diffuse Reflectance ◽  
Reaction Conditions ◽  
In Situ Drifts ◽  
Ft Ir

The reactivity of a Lu2O3-promoted Rh/Al2O3 catalyst in the CO/H2 reaction is reported. Methane, heavier hydrocarbons, methanol, and ethanol are obtained. In situ DRIFTS has been employed to record the infrared spectra under the actual reaction conditions. The structure of the observed COads DRIFTS bands has been resolved into its components. The production of oxygenates (methanol and ethanol) has been correlated with the results of the deconvolution calculation. Specific sites for the production of methanol and ethanol in the CO/H2 reaction over a Rh,Lu2O3/Al2O3 catalyst are proposed.

scholarly journals Enzymatic synthesis and phosphorolysis of 4(2)-thioxo- and 6(5)-azapyrimidine nucleosides by E. coli nucleoside phosphorylases

2016 ◽  
Vol 12 ◽  
pp. 2588-2601 ◽  
Author(s):  
Vladimir A Stepchenko ◽  
Anatoly I Miroshnikov ◽  
Frank Seela ◽  
Igor A Mikhailopulo
Keyword(s):  
Purine Nucleoside Phosphorylase ◽  
Reaction Conditions ◽  
E Coli ◽  
No Formation ◽  
Structural Peculiarities ◽  
Substrate Properties ◽  
Nucleoside Phosphorylases ◽  
Derivatives Of

The trans-2-deoxyribosylation of 4-thiouracil (4SUra) and 2-thiouracil (2SUra), as well as 6-azauracil, 6-azathymine and 6-aza-2-thiothymine was studied using dG and E. coli purine nucleoside phosphorylase (PNP) for the in situ generation of 2-deoxy-α-D-ribofuranose-1-phosphate (dRib-1P) followed by its coupling with the bases catalyzed by either E. coli thymidine (TP) or uridine (UP) phosphorylases. 4SUra revealed satisfactory substrate activity for UP and, unexpectedly, complete inertness for TP; no formation of 2’-deoxy-2-thiouridine (2SUd) was observed under analogous reaction conditions in the presence of UP and TP. On the contrary, 2SU, 2SUd, 4STd and 2STd are good substrates for both UP and TP; moreover, 2SU, 4STd and 2’-deoxy-5-azacytidine (Decitabine) are substrates for PNP and the phosphorolysis of the latter is reversible. Condensation of 2SUra and 5-azacytosine with dRib-1P (Ba salt) catalyzed by the accordant UP and PNP in Tris∙HCl buffer gave 2SUd and 2’-deoxy-5-azacytidine in 27% and 15% yields, respectively. 6-Azauracil and 6-azathymine showed good substrate properties for both TP and UP, whereas only TP recognizes 2-thio-6-azathymine as a substrate. 5-Phenyl and 5-tert-butyl derivatives of 6-azauracil and its 2-thioxo derivative were tested as substrates for UP and TP, and only 5-phenyl- and 5-tert-butyl-6-azauracils displayed very low substrate activity. The role of structural peculiarities and electronic properties in the substrate recognition by E. coli nucleoside phosphorylases is discussed.

Zinc Oxide/Polyaniline Transparent Conductive Film Prepared by In Situ Polymerization Deposition

2014 ◽  
Vol 997 ◽  
pp. 368-370
Author(s):  
Ping Zhong ◽  
Lin Xiu Cheng ◽  
Xing Lu
Keyword(s):  
Zinc Oxide ◽  
Oxidative Polymerization ◽  
Optimal Conditions ◽  
Chemical Oxidative Polymerization ◽  
Reaction Conditions ◽  
Transparent Conductive Film ◽  
Conductive Film

In this paper，ZnO/PANI transparent conductive film has been prepared by in situ chemical oxidative polymerization, APS as an oxidant. The conductivity and transmittance of ZnO/PANI was measured. It has been investigated of the effects of reaction conditions and the doping component on conductivity, transmissivity and adhesion. With the increase of doping ZnO, the conductivity of ZnO/PANI transparent conductive film, transmittance and adhesion reduced. The optimal conditions is that the concentration of An, APS and PVA are 0.75 mol / L, 0.8 mol / L and 0.5wt%, respectively.

57Fe Mössbauer Spectroscopic Study of the Geometrical Effects In the Catalytic Reactions with Intercalation Compounds

1982 ◽  
Vol 20 ◽  
Author(s):  
P.P. Vaishnava ◽  
P.A. Montano
Keyword(s):  
Ferric Chloride ◽  
Catalytic Reactions ◽  
Fischer Tropsch ◽  
Reaction Conditions ◽  
Intercalated Graphite ◽  
The Third ◽  
Intercalated Compounds ◽  
Catalytic Sites ◽  
Geometrical Effects

ABSTRACTIn situ 57Fe Mössbauer spectra are reported for the first-, higher-stage ferric chloride, and a mixed ferric chloride-potassium chloride intercalated graphite catalysts under reduction and Fischer-Tropsch reaction conditions. The mass spectroscopic measurements reveal a different catalytic selectivity for the three catalysts. The first two catalysts predominantly possess a higher selectivity for methane, whereas the third catalyst has higher selectivity for the formation of propane. The differences are attributed to geometrical effects in the catalytic sites of the intercalated compounds.

Sign in / Sign up

Export Citation Format

Share Document