| Abstract
| - A computational study with density functional theory (DFT) is carried out on the reaction between methylsulfinyl chloride (MSC) and methanol in the presence of trimethylamine, a process which is a generalmodel for two different methods used in practice for the obtention of chiral sulfoxides through dynamickinetic resolution. Two mechanistic options are considered: in one of them, chloride is initially displacedby the base (ion pair mechanism), whereas in the other, chloride stays bound to sulfur until its finaldisplacement by methoxy (neutral mechanism). In both cases, the approach of the alcohol to sulfur iscoupled with a hydrogen transfer from methanol to the oxo group of MSC in a single concerted transitionstate. The presence of a trimethylamine molecule facilitates substantially the reaction by reducing thenucleophilic substitution barrier by more than 10 kcal/mol through the formation of a N−H bond withthe hydrogen atom being transferred. The neutral mechanism presents a free energy barrier lower thanthe ion pair alternative and is thus preferred.
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