Electrophilic alkene sulfenylation with sulfinate esters

Area of Science:

• Organic Chemistry
• Synthetic Chemistry

Background:

• Sulfinate esters are versatile sulfur sources.
• Electrophilic addition and substitution reactions are fundamental in organic synthesis.

Purpose of the Study:

• To develop a novel electrophilic alkene sulfenylation method.
• To investigate the substrate-dependent reaction pathways.

Main Methods:

• Mild hydroiodic acid (HI) activation of sulfinate esters.
• Reaction with various alkenes (terminal, 1,2-disubstituted, cyclic, 1,1-diarylethenes).
• Mechanistic studies including control experiments and Hammett analyses.

Main Results:

• Selective synthesis of β-alkoxysulfides via electrophilic addition for most alkenes.
• Selective synthesis of alkenyl sulfides via electrophilic substitution for 1,1-diarylethenes.
• Identification of sulfur(II) electrophiles and episulfonium ion intermediates.

Conclusions:

• Sulfinate esters are effective precursors for electrophilic sulfur(II) species.
• Episulfonium ion formation is the rate-determining step.
• A mechanistic framework explains the divergence between addition and substitution pathways based on substrate.