N-Heterocyclic carbene-catalyzed formal cross-coupling reaction of α-haloenals with thiols: organocatalytic construction of sp2 carbon-sulfur bonds.

A novel N-heterocyclic carbene (NHC)-catalyzed formal cross-coupling reaction between α-haloenals and thiols was developed. In the presence of 5 mol% NHC precursors and 1.6 equiv. potassium carbonate, various thiols coupled with α-haloenals to produce α-thioenals in 53% to 91% yield and excellent Z-selectivity.