Theoretical Study of Nucleophilic Substitution at Sulfur in Sulfinyl Derivatives

Abstract

A series of gas-phase nucleophilic substitution reactions at sulfur of methanesulfinyl derivatives by small anions (chloride, cyanide, hydroxide, methoxide, amide, and phosphide, identical to the leaving group in each case) were examined by Hartree-Fock, MP2, and DFT computations. In most cases, substitution was found to follow an addition-elimination mechanism, resulting in a triple-well potential energy surface with small barriers of activation on either side of the central, tetracoordinate-sulfur minimum. The geometries of the central minima, as in the analogous methanesulfenyl cases, are unsymmetrical trigonal bipyramidal, with the nucleophiles and leaving groups occupying apical positions and the sulfur lone pair an equatorial position. The apparent exception, cyanide, may undergo an S(N)2 displacement.

Nucleophilic Substitution (SN2): Dependence on Nucleophile, Leaving Group, Central Atom, Substituents, and Solvent

“…These bridges are often involved in or affected by, redox processes, in which a disulfide bond may interconvert with a dithiol system . Bachrach and co‐workers, highlighted other reaction mechanisms to achieve S−S bond cleavage. Their work was expanded on by Ramos, Bickelhaupt, and co‐workers ,.…”

“…Orian and coworkers further investigated reactions involving other chalcogens by focusing on S N 2@S, S N 2@Se, and S N 2@Te . Bachrach and co‐workers studied simple acyclic also investigated cyclic sulfides, and sulfinyl derivatives . In the latter compounds, the additional oxygen ligand to sulfur does not have a marked effect on the energy surface and the reaction proceeds mainly through a triple‐well mechanism.…”

“…In the latter compounds, the additional oxygen ligand to sulfur does not have a marked effect on the energy surface and the reaction proceeds mainly through a triple‐well mechanism. The only exception found was with cyanide as the nucleophile, which showed a double‐well PES, albeit with a very small barrier . The study by Bachrach and Chamberlin on cyclic sulfides was the first step towards understanding the S N 2@S processes in biological systems.…”

The Synthesis of Sulfinylphthalimides and their Reactions with Some Nucleophiles in Dioxane

“…7 In a recent study, this reaction was explored for the particular case of sulfinyl chlorides. 8 Um et al Reported, along with kinetic evidence for a stepwise mechanism, the first spectroscopic observation of an intermediate in the reaction of a sulfinate ester with NaOEt in anhydrous EtOH. 9 A study of the kinetics and mechanism THE SYNTHESIS OF SULFINYLPHTHALIMIDES AND THEIR REACTIONS 2251 of the acid catalyzed hydrolysis of a series of N-(p-substitutedarylsulfinyl)phthalimides have been studied in concentrated aqueous mineral acids in our laboratory.…”

How does the Achiral Base Decide the Stereochemical Outcome in the Dynamic Kinetic Resolution of Sulfinyl Chlorides? A Computational Study

“…The study on the chlorine displacement [19] revealed that the alcohol reacts directly with MeSOCl following an addition/elimination mechanism originally proposed by Bachrach. [20] The absolute configuration of sulfur is decided in the addition step, which involves a hydrogen transfer from the alcohol to the sulfinyl oxygen of the substrate. The base participates into the mecha- Table 1.…”