Copper-Catalyzed Coupling Reactions of Cyclobutanone Oxime Esters with Sulfur Nucleophiles at Room Temperature

A copper-catalyzed iminyl radical-mediated C–C bond cleavage/cross-coupling tandem reaction of cyclobutanone oxime esters with aryl thiols in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) at room temperature was developed, and aryl cyanopropyl sulfides were smoothly synthesized in 20–88% yields. By altering the copper reagent and the molar ratio of cyclobutanone oxime ester/aryl thiol/DBU, substitutional product N-arylthio cyclobutanone imines were selectively generated in 50–91% yields. Using this protocol, C–S bond and N–S bond formations using aryl thiols as sulfur sources were realized under very mild conditions without the use of photocatalysis and electrocatalysis techniques.