Prolinamide plays a key role in promoting copper-catalyzed cycloaddition of azides and alkynes in aqueous media via unprecedented metallacycle intermediates

2021 ◽  
Author(s):  
Gargi Chakraborti ◽  
Tirtha Mandal ◽  
Rajkumar Jana ◽  
Ayan Datta ◽  
Jyotirmayee Dash
Keyword(s):  
Catalytic System ◽  
Aqueous Media ◽  
Terminal Alkynes ◽  
Aerobic Conditions ◽  
Wide Range

We herein delineate cycloaddition of a wide range of azides with terminal alkynes using catalytic CuI and a prolinamide ligand in aqueous media under aerobic conditions. The catalytic system can...

scholarly journals Bis-NHC–Ag/Pd(OAc)2 Catalytic System Catalyzed Transfer Hydrogenation Reaction

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 8
Author(s):  
Hui-Ju Chen ◽  
Chien-Cheng Chiu ◽  
Tsui Wang ◽  
Dong-Sheng Lee ◽  
Ta-Jung Lu
Keyword(s):  
Functional Groups ◽  
Catalytic System ◽  
High Efficiency ◽  
Aqueous Media ◽  
Hydrogenation Reaction ◽  
Transfer Hydrogenation ◽  
Terminal Alkynes ◽  
Wide Range ◽  
Transfer Hydrogenation Reaction

The bis-NHC–Ag/Pd(OAc)2 catalytic system (NHC = N-heterocyclic carbene), a combination of bis-NHC–Ag complex and Pd(OAc)2, was found to be a smart catalyst in the Pd-catalyzed transfer hydrogenation of various functionalized arenes and internal/terminal alkynes. The catalytic system demonstrated high efficiency for the reduction of a wide range of various functional groups such as carbonyls, alkynes, olefins, and nitro groups in good to excellent yields and high chemoselectivity for the reduction of functional groups. In addition, the protocol was successfully exploited to stereoselectivity for the transformation of alkynes to alkenes in aqueous media under air. This methodology successfully provided an alternative useful protocol for reducing various functional groups and a simple operational protocol for transfer hydrogenation.

scholarly journals The Homocoupling Reaction of Aromatic Terminal Alkynes by a Highly Active Palladium(II)/AgNO3 Cocatalyst in Aqueous Media Under Aerobic Conditions

Molecules ◽  
2016 ◽  
Vol 21 (5) ◽  
pp. 606 ◽  
Author(s):  
Mengping Guo ◽  
Bo Chen ◽  
Meiyun Lv ◽  
Xiuling Zhou ◽  
Yongju Wen ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Terminal Alkynes ◽  
Aerobic Conditions ◽  
Highly Active ◽  
Homocoupling Reaction

scholarly journals Ureido Functionalization through Amine-Urea Transamidation under Mild Reaction Conditions

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1583
Author(s):  
Natalia Guerrero-Alburquerque ◽  
Shanyu Zhao ◽  
Daniel Rentsch ◽  
Matthias M. Koebel ◽  
Marco Lattuada ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Reaction Times ◽  
Reaction Rates ◽  
Secondary Amines ◽  
Isocyanic Acid ◽  
Advantages And Disadvantages ◽  
Major Disadvantage ◽  
Wide Range ◽  
Potential Alternative ◽  
Full Conversion

Ureido-functionalized compounds play an indispensable role in important biochemical processes, as well as chemical synthesis and production. Isocyanates, and KOCN in particular, are the preferred reagents for the ureido functionalization of amine-bearing compounds. In this study, we evaluate the potential of urea as a reagent to graft ureido groups onto amines at relatively low temperatures (<100 °C) in aqueous media. Urea is an inexpensive, non-toxic and biocompatible potential alternative to KOCN for ureido functionalization. From as early as 1864, urea was the go-to reagent for polyurea polycondensation, before falling into disuse after the advent of isocyanate chemistry. We systematically re-investigate the advantages and disadvantages of urea for amine transamidation. High ureido-functionalization conversion was obtained for a wide range of substrates, including primary and secondary amines and amino acids. Reaction times are nearly independent of substrate and pH, but excess urea is required for practically feasible reaction rates. Near full conversion of amines into ureido can be achieved within 10 h at 90 °C and within 24 h at 80 °C, and much slower reaction rates were determined at lower temperatures. The importance of the urea/amine ratio and the temperature dependence of the reaction rates indicate that urea decomposition into an isocyanic acid or a carbamate intermediate is the rate-limiting step. The presence of water leads to a modest increase in reaction rates, but the full conversion of amino groups into ureido groups is also possible in the absence of water in neat alcohol, consistent with a reaction mechanism mediated by an isocyanic acid intermediate (where the water assists in the proton transfer). Hence, the reaction with urea avoids the use of toxic isocyanate reagents by in situ generation of the reactive isocyanate intermediate, but the requirement to separate the excess urea from the reaction product remains a major disadvantage.

Reactions of salicylaldehydes with activated terminal alkynes in aqueous media: synthesis of 3-substituted 4-hydroxy chromenes as potential cytotoxic agents

RSC Advances ◽  
2014 ◽  
Vol 4 (47) ◽  
pp. 24870 ◽  
Author(s):  
Shambhu Nath Singh ◽  
Ramu Bopanni ◽  
Sarva Jayaprakash ◽  
K. Venkateshwara Reddy ◽  
Mohd Ashraf Ashfaq ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Cytotoxic Agents ◽  
Terminal Alkynes

Cycloaddition of N-sulfonyl and N-sulfamoyl azides with alkynes in aqueous media for the selective synthesis of 1,2,3-triazoles

2021 ◽  
Author(s):  
Thumpati Prasanth ◽  
Gargi Chakraborti ◽  
Tirtha Mandal ◽  
Velayutham Ravichandiran ◽  
Jyotirmayee Dash
Keyword(s):  
Aqueous Media ◽  
Selective Synthesis ◽  
Terminal Alkynes ◽  
Amide Derivatives

The cycloaddition of N-sulfonyl and N-sulfamoyl azides with terminal alkynes generally produces amide derivatives via ketenimine intermediates. We herein delineate a Cu(I) catalyzed method using a prolinamide ligand that selectively...

scholarly journals C–C (alkynylation) vs C–O (ether) bond formation under Pd/C–Cu catalysis: synthesis and pharmacological evaluation of 4-alkynylthieno[2,3-d]pyrimidines

2011 ◽  
Vol 7 ◽  
pp. 338-345 ◽  
Author(s):  
Dhilli Rao Gorja ◽  
K Shiva Kumar ◽  
K Mukkanti ◽  
Manojit Pal
Keyword(s):  
Cytotoxic Activity ◽  
Catalytic System ◽  
High Selectivity ◽  
Bond Formation ◽  
Terminal Alkynes ◽  
Ether Bond ◽  
Pharmacological Evaluation

The Pd/C–CuI–PPh3 catalytic system facilitated C–C bond formation between 4-chlorothieno[2,3-d]pyrimidines and terminal alkynes in methanol with high selectivity without generating any significant side products arising from C–O bond formation between the chloro compounds and methanol. A variety of novel 4-alkynylthieno[2,3- d]pyrimidines were prepared via alkynylation of 4-chlorothieno[2,3-d]pyrimidines in good to excellent yields. Some of the compounds synthesized were tested for cytotoxic activity in vitro.

scholarly journals Formation of flavorant–propylene Glycol Adducts With Novel Toxicological Properties in Chemically Unstable E-Cigarette Liquids

2018 ◽  
Vol 21 (9) ◽  
pp. 1248-1258 ◽  
Author(s):  
Hanno C Erythropel ◽  
Sairam V Jabba ◽  
Tamara M DeWinter ◽  
Melissa Mendizabal ◽  
Paul T Anastas ◽  
...  
Keyword(s):  
Propylene Glycol ◽  
Electronic Cigarettes ◽  
Aqueous Media ◽  
Chemical Species ◽  
Resonance Spectroscopy ◽  
Reaction Products ◽  
Chemical Systems ◽  
Toxicological Effects ◽  
Wide Range ◽  
Irritant Receptors

Abstract Introduction “Vaping” electronic cigarettes (e-cigarettes) is increasingly popular with youth, driven by the wide range of available flavors, often created using flavor aldehydes. The objective of this study was to examine whether flavor aldehydes remain stable in e-cigarette liquids or whether they undergo chemical reactions, forming novel chemical species that may cause harm to the user. Methods Gas chromatography was used to determine concentrations of flavor aldehydes and reaction products in e-liquids and vapor generated from a commercial e-cigarette. Stability of the detected reaction products in aqueous media was monitored by ultraviolet spectroscopy and nuclear magnetic resonance spectroscopy, and their effects on irritant receptors determined by fluorescent calcium imaging in HEK-293T cells. Results Flavor aldehydes including benzaldehyde, cinnamaldehyde, citral, ethylvanillin, and vanillin rapidly reacted with the e-liquid solvent propylene glycol (PG) after mixing, and upward of 40% of flavor aldehyde content was converted to flavor aldehyde PG acetals, which were also detected in commercial e-liquids. Vaping experiments showed carryover rates of 50%–80% of acetals to e-cigarette vapor. Acetals remained stable in physiological aqueous solution, with half-lives above 36 hours, suggesting they persist when inhaled by the user. Acetals activated aldehyde-sensitive TRPA1 irritant receptors and aldehyde-insensitive TRPV1 irritant receptors. Conclusions E-liquids are potentially reactive chemical systems in which new compounds can form after mixing of constituents and during storage, as demonstrated here for flavor aldehyde PG acetals, with unexpected toxicological effects. For regulatory purposes, a rigorous process is advised to monitor the potentially changing composition of e-liquids and e-vapors over time, to identify possible health hazards. Implications This study demonstrates that e-cigarette liquids can be chemically unstable, with reactions occurring between flavorant and solvent components immediately after mixing at room temperature. The resulting compounds have toxicological properties that differ from either the flavorants or solvent components. These findings suggest that the reporting of manufacturing ingredients of e-liquids is insufficient for a safety assessment. The establishment of an analytical workflow to detect newly formed compounds in e-liquids and their potential toxicological effects is imperative for regulatory risk analysis.

Novel Intramolecular Allylindination of Terminal Alkynes in Aqueous Media.

ChemInform ◽  
2003 ◽  
Vol 34 (11) ◽  
Author(s):  
Matthew M. Salter ◽  
Sofia Sardo-Inffiri
Keyword(s):  
Aqueous Media ◽  
Terminal Alkynes

scholarly journals Charge Compensation in Europium-Doped Hafnia Nanoparticles: Solvothermal Synthesis and Colloidal Dispersion

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1042
Author(s):  
Xavier H. Guichard ◽  
Francesco Bernasconi ◽  
Alessandro Lauria
Keyword(s):  
Low Temperature ◽  
Hafnium Oxide ◽  
Aqueous Media ◽  
Charge Compensation ◽  
Colloidal Dispersion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Direct Formation ◽  
Enhanced Luminescence

Effective charge compensation of europium in hafnium oxide nanoparticles was achieved at low temperature, allowing high doping incorporation (up to 6 at.%) and enhanced luminescence. The efficiency of the incorporation and charge compensation was confirmed by scanning electron microscope energy dispersive X-ray spectroscopy and powder X-ray diffraction measurements. Despite the known polymorphism of hafnium oxide, when doped to a concentration above 3 at.%, only the pure monoclinic phase was observed up to 6 at.% of europium. Furthermore, the low-temperature solvothermal route allowed the direct formation of stable dispersions of the synthesized material over a wide range of concentrations in aqueous media. The dispersions were studied by diffuse light scattering (DLS) to evaluate their quality and by photoluminescence to investigate the incorporation of the dopants into the lattice.

Sign in / Sign up

Export Citation Format

Share Document