The Pummerer rearrangement is a useful transformation of sulfoxides that converts an activated sulfur center into an α-functionalized sulfide. Its value comes from the controlled generation of reactive thionium-ion intermediates that can be intercepted by a range of nucleophiles.
General reaction pathway
A typical sequence begins with activation of the sulfoxide oxygen by an electrophilic reagent. Elimination then forms a thionium species, followed by nucleophilic attack at the carbon adjacent to sulfur. The exact outcome depends on substrate structure, activator, solvent, temperature, and nucleophile.
Applications in synthesis
Pummerer chemistry is used in carbon–heteroatom bond formation, heterocycle construction, and strategic functional-group interconversion. Modified variants can broaden substrate scope or enable intramolecular cyclization.
Project considerations
Reaction screening should consider competing elimination, overactivation, and the stability of the intermediate. Analytical monitoring and careful control of water content often help improve selectivity and reproducibility.