Nucleophilic Attack on Some Isothiazolium Salts

1973 ◽  
Vol 51 (18) ◽  
pp. 3081-3086 ◽  
Author(s):  
David M. Mckinnon ◽  
Mohamed E. Hassan
Keyword(s):  
Hydrogen Sulfide ◽  
Sulfur Atom ◽  
Nucleophilic Attack ◽  
Isothiazolium Salts

A variety of isothiazolium salts has been prepared and allowed to react with sodium benzoylacetate. 2-Benzoylthiophenes are obtained, suggesting that the position of initial nucleophilic attack is at the sulfur atom of the heterocyclic cation. Reaction with hydrogen sulfide gave acyclic reduction products, or 1,2-dithiole derivatives, depending on the type of substituent on nitrogen in the isothiazolium salts.

The conversions of isothiazolium salts into thiophenecarboxylic ester derivatives

1984 ◽  
Vol 62 (8) ◽  
pp. 1580-1584 ◽  
Author(s):  
David M. McKinnon ◽  
K. Ann Duncan ◽  
Lesley M. Millar
Keyword(s):  
Sulfur Atom ◽  
Nucleophilic Attack ◽  
Carboxylic Ester ◽  
Pyrrole Derivative ◽  
Isothiazolium Salts ◽  
Derivatives Of

Several 3-aminothiophene-2-carboxylic ester derivatives are made by reaction of potassium 3-ethoxy-3-oxopropanoate with isothiazolium salts or by reaction with 2-ethoxy-2-oxoethylidenedimethylsulfurane. In the latter case deaminated products are also isolated. These products are consistent with initial nucleophilic attack on the sulfur atom of the isothiazolium salt. In one case a pyrrole derivative is formed by a novel rearrangement of an intermediate aziridine derivative. Some further derivatives of 3-benzylaminobenzo[b]thiophene are described.

scholarly journals QUANTUM-CHEMICAL STUDY OF THE REACTION MECHANISM 1,2-ETHANEDIIOL WITH 1,3-DICHLOROPROPENE

2020 ◽  
Vol 2018 (1) ◽  
pp. 56-57
Author(s):  
Elena Chirkina ◽  
Leonid Krivdin ◽  
Nikolay Korchevin
Keyword(s):  
Carbon Atom ◽  
Sulfur Atom ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Thiol Group ◽  
Chemical Study ◽  
Nucleophilic Attack ◽  
Substitution Product ◽  
Reaction Proceeds ◽  
Theoretical Mechanism

The theoretical mechanism of the interaction of 1,3-dichloropropene with 1,2- ethanedithiol in the system "hydrazine hydrate-KOH" has been proposed by the method of B3LYP / 6- 311 ++ G (d, p) in the framework of the theory of the electron-density functional according to which the reaction proceeds successively in several stages, including the nucleophilic substitution of the chlorine atom present in the sp3-hybridized carbon atom with a sulfur atom to form a mono-substitution product that undergoes a prototropic allylic rearrangement that migrates the double bond to the sulfur atom, followed by closure in the dithiolane cycle due to the nucleophilic attack of the sulfide anion of the second thiol group of the reagent per carbon atom located in the γ-position with respect to the second chlorine atom.

scholarly journals THEORETICAL STUDY OF THE REACTION MECHANISM 1,2-ETHANEDIIOL WITH 1,3-DICHLOROPROPENE

2020 ◽  
Vol 2018 (1) ◽  
pp. 68-77
Author(s):  
Elena Chirkina ◽  
Leonid Krivdin ◽  
Nikolay Korchevin
Keyword(s):  
Carbon Atom ◽  
Chlorine Atom ◽  
Sulfur Atom ◽  
Density Functional ◽  
Theoretical Study ◽  
Thiol Group ◽  
Nucleophilic Attack ◽  
Substitution Product ◽  
Reaction Proceeds ◽  
Theoretical Mechanism

The theoretical mechanism of the interaction of 1,3-dichloropropene with 1,2-ethanedithiol in the system "hydrazine hydrate-KOH" has been proposed by the method of B3LYP / 6-311 ++ G (d, p) in the framework of the theory of the electron-density functional according to which the reaction proceeds successively in several stages, including the nucleophilic substitution of the chlorine atom present in the sp3-hybridized carbon atom with a sulfur atom to form a mono-substitution product that undergoes a prototropic allylic rearrangement that migrates the double bond to the sulfur atom, followed by closure in the dithiolane cycle due to the nucleophilic attack of the sulfide anion of the second thiol group of the reagent per carbon atom located in the γ-position with respect to the second chlorine atom.

The reactions of isothiazolium salts with selected nucleophilic reagents. The preparation of thieno[2,3-c]isothiazolium salts

1977 ◽  
Vol 55 (7) ◽  
pp. 1123-1128 ◽  
Author(s):  
David M. McKinnon ◽  
Mohammed E. R. Hassan ◽  
Mohinder Chauhan
Keyword(s):  
Ring Opening ◽  
Nucleophilic Attack ◽  
Isothiazolium Salts ◽  
Thiophene Derivatives ◽  
Nucleophilic Reagents

Isothiazolium salts react with a number of carbanions by attack on sulfur. Thiophene derivatives, formed by ring opening and recyclization, are often products but with cyclopentadiene, pseudoazulene products are obtained. 3-Amino-2-acylthiophenes, prepared by suitable nucleophilic attack, are synthetic precursors of thieno[2,3-c]isothiazolium salts

Neighbouring group participation of thiol through aldehyde group assisted thiolysis of active ether: ratiometric and vapor phase fast detection of hydrogen sulfide in mixed aqueous media

2015 ◽  
Vol 39 (7) ◽  
pp. 5669-5675 ◽  
Author(s):  
Avijit Kumar Das ◽  
Shyamaprosad Goswami ◽  
Ching Kheng Quah ◽  
Hoong-Kun Fun
Keyword(s):  
Hydrogen Sulfide ◽  
Vapor Phase ◽  
Aqueous Media ◽  
Aldehyde Group ◽  
Nucleophilic Attack ◽  
Ether Linkage ◽  
Fast Detection ◽  
Group Participation ◽  
Neighbouring Group Participation

Ratiometric and fast detection of H2S via NGP of thiol rather than direct nucleophilic attack to cleave active ether linkage.

scholarly journals Structural Analysis of an L-Cysteine Desulfurase from an Ssp DNA Phosphorothioation System

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Liqiong Liu ◽  
Susu Jiang ◽  
Mai Xing ◽  
Chao Chen ◽  
Chongde Lai ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Conformational Change ◽  
Molecular Mechanism ◽  
Sulfur Atom ◽  
Nucleophilic Attack ◽  
Nonbridging Oxygen ◽  
Long Distance ◽  
Cysteine Desulfurase ◽  
Modification System ◽  
Pt Modification

ABSTRACT DNA phosphorothioate (PT) modification, in which the nonbridging oxygen in the sugar-phosphate backbone is substituted by sulfur, is catalyzed by DndABCDE or SspABCD in a double-stranded or single-stranded manner, respectively. In Dnd and Ssp systems, mobilization of sulfur in PT formation starts with the activation of the sulfur atom of cysteine catalyzed by the DndA and SspA cysteine desulfurases, respectively. Despite playing the same biochemical role, SspA cannot be functionally replaced by DndA, indicating its unique physiological properties. In this study, we solved the crystal structure of Vibrio cyclitrophicus SspA in complex with its natural substrate, cysteine, and cofactor, pyridoxal phosphate (PLP), at a resolution of 1.80 Å. Our solved structure revealed the molecular mechanism that SspA employs to recognize its cysteine substrate and PLP cofactor, suggesting a common binding mode shared by cysteine desulfurases. In addition, although the distance between the catalytic Cys314 and the substrate cysteine is 8.9 Å, which is too far for direct interaction, our structural modeling and biochemical analysis revealed a conformational change in the active site region toward the cysteine substrate to move them close to each other to facilitate the nucleophilic attack. Finally, the pulldown analysis showed that SspA could form a complex with SspD, an ATP pyrophosphatase, suggesting that SspD might potentially accept the activated sulfur atom directly from SspA, providing further insights into the biochemical pathway of Ssp-mediated PT modification. IMPORTANCE Apart from its roles in Fe-S cluster assembly, tRNA thiolation, and sulfur-containing cofactor biosynthesis, cysteine desulfurase serves as a sulfur donor in the DNA PT modification, in which a sulfur atom substitutes a nonbridging oxygen in the DNA phosphodiester backbone. The initial sulfur mobilization from l-cysteine is catalyzed by the SspA cysteine desulfurase in the SspABCD-mediated DNA PT modification system. By determining the crystal structure of SspA, the study presents the molecular mechanism that SspA employs to recognize its cysteine substrate and PLP cofactor. To overcome the long distance (8.9 Å) between the catalytic Cys314 and the cysteine substrate, a conformational change occurs to bring Cys314 to the vicinity of the substrate, allowing for nucleophilic attack.

Cleavage of the Sulfur–Sulfur Bond in 2,4-Dinitrophenyl-4-substituted-phenyl Disulfides by trans-[IrCl(CO) (PPh3)2]. A Kinetic Study

1973 ◽  
Vol 51 (22) ◽  
pp. 3790-3794 ◽  
Author(s):  
Chiu T. Lam ◽  
Caesar V. Senoff
Keyword(s):  
Transition State ◽  
Kinetic Study ◽  
Sulfur Atom ◽  
Activation Parameters ◽  
Initial Step ◽  
Second Order ◽  
Nucleophilic Attack ◽  
Kinetics Of ◽  
Sulfur Bond

The kinetics of the reaction between trans-[IrCl(CO)(PPh3)2] and a series of 2,4-dinitrophenyl-4-substituted-phenyl disulfides, YC6H4SSC6H3(NO2)2 (Y = Br, F, H, CH3, or CH3O) have been investigated in toluene between 70 and 90°. These reactions were found to follow simple second order kinetics, rate = k2[IrCl(CO)(PPh3)2][YC6H4SSC6H3(NO2)2]. The rates of reaction were also found to be insensitive to the nature of the para substituent, Y. This fact together with the observed activation parameters, ΔH≠ ~ 17 kcal mol−1 and ΔS≠ ~ − 19 cal mol−1 deg−1, have been interpreted as indicating that the initial step in these reactions involves a nucleophilic attack by the iridium atom at the sulfur atom bonded to the 2,4-dinitrophenyl group, followed by the formation of a three-centered transition state. An overall mechanism for these reactions is presented and discussed.

Trifluoromethylsulfonyl aryl derivatives: competitive nucleophilic attack at an aromatic carbon and at the sulfur atom of an aromatic SO2CF3 group

1980 ◽  
Vol 58 (1) ◽  
pp. 65-71 ◽  
Author(s):  
François Terrier ◽  
Jean Morel ◽  
Marie-José Pouet ◽  
Marie-Paule Simonnin
Keyword(s):  
Nitro Group ◽  
Sulfur Atom ◽  
Negative Charge ◽  
Chemical Shifts ◽  
Nucleophilic Attack ◽  
Aromatic Carbon ◽  
Methoxide Ion ◽  
Aryl Methyl

The reaction of methoxide ion with 2-nitro-4-trifluoromethylsulfonylanisole, 4-nitro-2-triftuoromethylsulfonylanisole and 2,4- bis(trifluoromethylsulfonyl)anisole in DMSO has been studied by 1H and 19F nmr. Evidence for the transient formation of gem-dimethoxy σ-adducts arising from nucleophilic attack at the aromatic C1 carbon is given. Concurrent methoxide ion attack occurs at the sulfur atom of the SO2CF3 group to give the aryl methyl sulfonates ArSO3CH3, which are slowly converted into aryl sulfonates ArSO3−. The 1H chemical shifts of the anisoles are consistent with a greater electron-withdrawing effect of the SO2CF3 group compared to the nitro group. In contrast, a 4-nitro group appears to be more efficient than a 4-SO2CF3 group in delocalizing the negative charge of the σ-adducts.

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