Alkyllithiums as Alkylating Agents: Regioselective Alkylation in the Semi-Bay Region of Polycyclic Azaarenes†

1996 ◽  
Vol 61 (5) ◽  
pp. 1863-1866 ◽  
Author(s):  
Jayanta K. Ray ◽  
Bidhan C. Roy ◽  
Gandhi K. Kar
Keyword(s):  
Alkylating Agents ◽  
Regioselective Alkylation

Magnesium-Catalyzed N2-Regioselective Alkylation of 3-Substituted Pyrazoles

Synlett ◽  
2019 ◽  
Vol 31 (06) ◽  
pp. 595-599
Author(s):  
Di Xu ◽  
Lena Frank ◽  
Tina Nguyen ◽  
Andreas Stumpf ◽  
David Russell ◽  
...  
Keyword(s):  
Alkylating Agents ◽  
New Method ◽  
Regioselective Alkylation ◽  
Substituted Pyrazoles

A highly regioselective Mg-catalyzed alkylation of 3-substituted pyrazoles has been developed to provide N2-alkylated regioisomers. Using α-bromoacetates and acetamides as alkylating agents, this new method was applied to a variety of 3-substituted and 3,4-disubstituted pyrazoles to produce the N2-alkylated products with high regioselectivities ranging from 76:24 to 99:1 and 44–90% yields.

Synthesis and Antioxidant Activity of Novel 5-amino-2-alkyl/glycosylthio-1,3,4- thiadiazoles: Regioselective Alkylation and Glycosylation of the 5-amino-1,3,4- thiadiazole-2-thiol Scaffold

2019 ◽  
Vol 16 (5) ◽  
pp. 801-809
Author(s):  
El Sayed H. El Ashry ◽  
El Sayed Ramadan ◽  
Mohammed R. Amer ◽  
Yeldez El Kilany ◽  
Mohamed E. I. Badawy ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Alkylating Agents ◽  
Radical Scavenging ◽  
Free Radical Scavenging ◽  
Antioxidant Compounds ◽  
Standard Drug ◽  
1H And 13C Nmr ◽  
Discovery Studio ◽  
Regioselective Alkylation ◽  
Ft Ir

Objective: 5-Amino-2-alkyl/glycosylthio-1,3,4-thiadiazoles have been synthesized by the reaction of 5-amino-1,3,4-thiadiazole-2-thiol with a variety of alkylating agents or glycosyl halides in the presence of anhydrous potassium carbonate in dry acetone. Methods: The structures of the newly synthesized compounds have been established based on their spectral data (FT-IR, 1H- and 13C-NMR) and mass spectrometry. They were tested for their antioxidant behaviour by the use of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method. The in silico pharmacokinetics ADME properties of the potent antioxidant compounds were investigated by using Accelrys Discovery Studio (DS) 2.5 software. Results and Conclusion: Regioselective alkylation and glycosylation of 5-amino-1,3,4-thiadiazole-2-thiol were noticed during its reaction with alkylating agents and glycosyl halides. Alkylating agents gave the Sfunctionalized derivatives, while the acetylated glycosyl halides afforded the S-glycosylated products together with their respective N-acetyl derivatives. The benzoylated glycosyl halide behaved in a different manner and gave N-glycoside analogue of 1,3,4-thiadiazole-2(3H)-thione, in addition to the expected sulfanyl S-glycoside. Most of the synthesized compounds showed noticeable antioxidant activity with respect to ceftriaxone as a standard drug. Some of the most active compounds showed acceptable predicted pharmacokinetics and druglikeness properties.

Photocatalytic Alkylation of Pyrroles and Indoles with α-Diazo Esters

2019 ◽  
Author(s):  
Łukasz Ciszewski ◽  
Jakub Durka ◽  
Dorota Gryko
Keyword(s):  
Aromatic Compounds ◽  
Reaction Pathway ◽  
Alkylating Agents ◽  
Catalytic Amount ◽  
Radical Formation ◽  
Reaction Selectivity ◽  
Diazo Esters ◽  
Electron Withdrawing Substituents

This article describes direct photoalkylation of electron-rich aromatic compounds with diazo compoiunds. C-2 alkylated indoles and pyrroles are obtained with good yields even though the photocatalyst (Ru(bpy)3Cl2) loading is as low as 0.075 mol %. For substrates bearing electron-withdrawing substituents the addition of a catalytic amount of N,N-dimethyl-4-methoxyaniline is required. Both EWG-EWG and EWG-EDG substituted diazo esters are suitable as alkylating agents. The reaction selectivity and mechanistic experiments suggest that carbenes/carbenoid intermediates are not involved in the reaction pathway, instead radical formation is proposed.

Hydrogeochemistry of Toxic Elements in Urbanized Geotechnical Systems

1997 ◽  
Vol 32 (3) ◽  
pp. 523-550
Author(s):  
S.N. Volkov
Keyword(s):  
Heavy Metals ◽  
Toxic Elements ◽  
Life Support ◽  
Alkylating Agents ◽  
Pollution Sources ◽  
The Urals

Abstract In urbanized geotechnical systems (UGSs), the majority of problems related to the ecological hydrochemistry of Cd, Pb, Ni and other heavy metals are the result of emergent characteristics of a system as a whole as opposed to individual pollution sources. In petrochemical UGSs, pollution of the environment from compounds containing methylating or alkylating agents results in an increase in the mobility of Cd, Pb, Ni, Cr and As. This process is controlled by environmental and microclimatic factors rather than by pollution sources. Under conditions of predominant dust and element effects, geo-chemically paradoxical associations of Cd with Ni, Mn and Cr can be formed in the main life support media in mining and metallurgical UGSs. Uncontrolled processes of hydrochemical interactions take place in complex multifunctional UGSs, leading to a change in speciation of heavy metals, particularly cadmium. This report is part of a 5-year study of the geotechnical systems in the Urals.

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