CuI/L-Proline-Catalyzed Synthesis of Vinyl Sulfides in 95% Alcohol

Abstract

A method for the synthesis of vinyl sulfides using the simple CuI/L-proline as a catalyst system is reported. The best yields were obtained in the 95% ethanol with 10 mol% CuI, 20 mol% L-proline, and 1.2 equiv of K₂CO₃. The amino acids act as base and excellent promoter for the copper-catalyzed coupling reactions, and this protocol tolerates both aromatic and heterocyclic thiols and avoids using other expensive additives.

Keywords:

• Cross-coupling reaction
• L-proline
• thiols
• vinyl sulfide

ACKNOWLEDGMENT

This work was funded by the Natural Science Foundation of Zhejiang Province, PR China (Project Y407240).

Notes

^a Reaction conditions: 10 mol% CuI, 20 mol% L-proline, and 1.2 equiv of K₂CO₃ in 5–10 ml above solvent at 80°C under N₂ atmosphere.

^b Isolated yields after reaction 8 h.

^a Reaction conditions: 3-iodo-cyclohexenone (2.0 mmol), 4-flurothiophenol (2.0 mmol), 10 mol% CuI, 20 mol% L-proline, and 1.2 equiv of K₂CO₃ in 10 ml of 95% EtOH at reflux under N₂ atmosphere.

^b Isolated yields.

^c Functional group is –SH.