Radical Functionalization of Thioglycosides in Aqueous Medium

2020 ◽  
Author(s):  
Sarbjeet Kaur ◽  
dominic luciano ◽  
gaoyuan zhao ◽  
Ting Wang
Keyword(s):  
Visible Light ◽  
Aqueous Medium ◽  
Reaction Medium ◽  
Reaction Pathways ◽  
Buffer System ◽  
Ene Reaction ◽  
Thiyl Radicals ◽  
Disulfide Formation ◽  
Basic Reaction ◽  
Radical Functionalization

<p>A visible-light-mediated thiol-ene reaction is successfully operated in aqueous medium. Organic photoredox catalyst (9-mesityl-10-methylacridinum tetrafluoroborate) is used to initiate the radical process to generate thiyl radicals upon light irradiation. Two reaction pathways are discovered in different aqueous buffer system. Thiol-ene adduct is preferred in acidity reaction medium; while disulfide formation is found to be favored in basic reaction medium. Moreover, a visible-light-mediated modified Danishefsky-Wan desulfurization is used to convert thioglycoside to highly substituted tetrahydropyran ring.</p>

scholarly journals Radical Functionalization of Thioglycosides in Aqueous Medium

2020 ◽  
Author(s):  
Sarbjeet Kaur ◽  
dominic luciano ◽  
gaoyuan zhao ◽  
Ting Wang
Keyword(s):  
Visible Light ◽  
Aqueous Medium ◽  
Reaction Medium ◽  
Reaction Pathways ◽  
Buffer System ◽  
Ene Reaction ◽  
Thiyl Radicals ◽  
Disulfide Formation ◽  
Basic Reaction ◽  
Radical Functionalization

<p>A visible-light-mediated thiol-ene reaction is successfully operated in aqueous medium. Organic photoredox catalyst (9-mesityl-10-methylacridinum tetrafluoroborate) is used to initiate the radical process to generate thiyl radicals upon light irradiation. Two reaction pathways are discovered in different aqueous buffer system. Thiol-ene adduct is preferred in acidity reaction medium; while disulfide formation is found to be favored in basic reaction medium. Moreover, a visible-light-mediated modified Danishefsky-Wan desulfurization is used to convert thioglycoside to highly substituted tetrahydropyran ring.</p>

Chlorination of 2,4,6-trichlorophenol in acidic aqueous medium

1985 ◽  
Vol 50 (8) ◽  
pp. 1842-1851 ◽  
Author(s):  
Petr Švec
Keyword(s):  
Reaction Mechanism ◽  
Aqueous Medium ◽  
Hydrogen Chloride ◽  
Reaction Medium ◽  
Model Experiments ◽  
Sulfuric And Hydrochloric Acids

The course of chlorination of 2,4,6-trichlorophenol (I) in water and approximately 20% sulfuric and hydrochloric acids has been investigated. In all these media the reaction gives primarily 2,4,6,6-tetrachloro-2,4-cyclohexadienone (II) which is subsequently chlorinated under formation of polychlorinated alicyclic ketones or isomerized to give the more stable 2,4,6,6-tetrachloro-2,5-cyclohexadienone (III), the precursor of further arising chlorinated 1,4-benzoquinones. The ratio of the arising polychlorinated alicyclic ketones to chlorinated 1,4-benzoquinones is significantly influenced by concentration of hydrogen chloride in the reaction medium. On the basis of model experiments, the reaction mechanism of exhaustive chlorination of 2,4,6-trichlorophenol has been suggested.

Photoassisted Production of O2-• and H2 in Aqueous Medium Stimulated by Polythiophene in ZSM-5 Zeolite Channels

1999 ◽  
Vol 64 (1) ◽  
pp. 149-156 ◽  
Author(s):  
Gabriel Čík ◽  
František Šeršeň ◽  
Alena Bumbálová
Keyword(s):  
Reactive Oxygen Species ◽  
Ion Exchange ◽  
Visible Light ◽  
Aqueous Medium ◽  
Exchange Reaction ◽  
Epr Spectroscopy ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Water Reduction ◽  
Ion Exchange Reaction

The formation of reactive oxygen species due to irradiation by a visible light of the polythiophene deposited in ZSM-5 zeolite channels in aqueous medium has been studied. Polymerization of thiophene was carried out in zeolite channels after the ion-exchange reaction of Na+ for Fe3+. By means of EPR spectroscopy, the temporarily generated 1O2 in irradiated aqueous medium was proved. The formation of O2-• was confirmed by the reduction of Fe3+-cytochrome c. Irradiation led to the water reduction to hydrogen.

scholarly journals On the Reaction Pathways and Growth Mechanisms of LiNbO3 Nanocrystals from the Non-Aqueous Solvothermal Alkoxide Route

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 154
Author(s):  
Mathias Urbain ◽  
Florian Riporto ◽  
Sandrine Beauquis ◽  
Virginie Monnier ◽  
Jean-Christophe Marty ◽  
...  
Keyword(s):  
Colloidal Stability ◽  
Formation Rate ◽  
Reaction Medium ◽  
Precursor Solution ◽  
Medium Composition ◽  
Shape Anisotropy ◽  
Reaction Pathways ◽  
Growth Mechanisms ◽  
Shape Distribution ◽  
Size And Shape

Phase-pure, highly crystalline sub-50 nm LiNbO3 nanocrystals were prepared from a non-aqueous solvothermal process for 72 h at 230 °C and a commercial precursor solution of mixed lithium niobium ethoxide in its parent alcohol. A systematic variation of the reaction medium composition with the addition of different amounts of co-solvent including butanol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol resulted in the formation of nanocrystals of adjustable mean size and shape anisotropy, as demonstrated from XRD measurements and TEM imaging. Colloidal stability of ethanol- and water-based suspensions was evaluated from dynamic light scattering (DLS)/zeta potential studies and correlated with FTIR data. Thanks to the evolution in the nanocrystal size and shape distribution we observed, as well as to the available literature on the alkoxide chemistry, the reaction pathways and growth mechanisms were finally discussed with a special attention on the monomer formation rate, leading to the nucleation step. The polar, non-perovskite crystalline structure of LiNbO3 was also evidenced to play a major role in the nanocrystal shape anisotropy.

Enantioselective Radical Functionalization of Imines and Iminium Intermediates via Visible Light Photoredox Catalysis

Synthesis ◽  
2020 ◽  
Author(s):  
Jia-Jia Zhao ◽  
Hong-Hao Zhang ◽  
Shouyun Yu
Keyword(s):  
Visible Light ◽  
Asymmetric Synthesis ◽  
Carbonyl Compounds ◽  
Asymmetric Reduction ◽  
Chemical Transformations ◽  
Photoredox Catalysis ◽  
Radical Coupling ◽  
Mild Conditions ◽  
Iminium Ions ◽  
Radical Functionalization

Visible light photoredox catalysis has recently emerged as a powerful tool for the development of new and valuable chemical transformations under mild conditions. Visible-light promoted enantioselective radical transformations of imines and iminium intermediates provide new opportunities for the asymmetric synthesis of amines and asymmetric β-functionalization of unsaturated carbonyl compounds. In this review, the advance in the catalytic asymmetric radical functionalization of imines, as well as iminium intermediates, are summarized. 1 Introduction 2 The enantioselective radical functionalization of imines 2.1 Asymmetric reduction 2.2 Asymmetric cyclization 2.3 Asymmetric addition 2.4 Asymmetric radical coupling 3 The enantioselective radical functionalization of iminium ions 3.1 Asymmetric radical alkylation 3.2 Asymmetric radical acylation 4 Conclusion

Visible light-induced direct conversion of aldehydes into nitriles in aqueous medium using Co@g-C3N4 as photocatalyst

2019 ◽  
Vol 119 ◽  
pp. 76-81 ◽  
Author(s):  
Fooleswar Verma ◽  
Prashant Shukla ◽  
Smita R. Bhardiya ◽  
Manorama Singh ◽  
Ankita Rai ◽  
...  
Keyword(s):  
Visible Light ◽  
Aqueous Medium ◽  
Direct Conversion

A novel chemosensor with visible light excitability for sensing CN− in aqueous medium and living cells via a Cu2+ displacement approach

2017 ◽  
Vol 9 (2) ◽  
pp. 259-266 ◽  
Author(s):  
Liyuan Qin ◽  
Lingjie Hou ◽  
Jia Feng ◽  
Jianbin Chao ◽  
Yu Wang ◽  
...  
Keyword(s):  
Visible Light ◽  
Aqueous Medium ◽  
Living Cells ◽  
Receptor System ◽  
System L ◽  
Displacement Approach

A new and simple julolidine based molecular receptor system L linked to 4-phenylsemicarbazide through an imine moiety has been synthesized and characterized.

Metal-Free Iodoperfluoroalkylation: Photocatalysis versus Frustrated Lewis Pair Catalysis

Synthesis ◽  
2020 ◽  
Vol 53 (01) ◽  
pp. 123-134
Author(s):  
Constantin Czekelius ◽  
Lucas Helmecke ◽  
Michael Spittler ◽  
Bernd M. Schmidt
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Light Irradiation ◽  
Reaction Pathways ◽  
Frustrated Lewis Pairs ◽  
Metal Free ◽  
Comprehensive Account ◽  
Frustrated Lewis Pair ◽  
Catalytic Metal ◽  
Lewis Pairs

A comparison of two catalytic, metal-free iodoperfluoro­alkylation protocols is presented. Frustrated Lewis pairs [ t Bu3P/B(C6F5)3] or phosphines/phosphites under visible light irradiation efficiently mediate the functionalization of non-activated alkenes and alkynes. A comprehensive account of the corresponding substrate scopes as well as insights into the mechanistic details of both reaction pathways are provided.

Nitroacenaphthene as a New Photocatalyst for the Synthesis of Sulfonyl Amidines

Synthesis ◽  
2019 ◽  
Vol 51 (23) ◽  
pp. 4425-4433
Author(s):  
Yong Jian ◽  
Ming Chen ◽  
Chao Yang ◽  
Wujiong Xia
Keyword(s):  
Visible Light ◽  
Small Molecule ◽  
Reaction Pathways ◽  
Visible Light Photocatalyst ◽  
Mild Conditions ◽  
Sulfonyl Azides ◽  
Site Selective ◽  
First Time

A small molecule, namely nitroacenaphthene, is reported for the first time as a recyclable visible-light photocatalyst for the construction of the C=N bond from sulfonyl azides and amines. This scalable, site-selective protocol provides a convenient way to access various sulfonyl amidines under mild conditions. Two reaction pathways are proposed, according to different transformation patterns.

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