Efficient Protocol for Stereoselective Epoxidation of Cinnamic Esters Using TsNBr₂

Abstract

An efficient method has been developed for the synthesis of epoxide from cinnamic esters without any catalyst. The reaction was performed in CH₃CN–water (4:1) using N,N-dibromo-p-toluenesulfonamide (TsNBr₂) in alkaline conditions. This procedure can be utilized for stereoselective synthesis of epoxides from cinnamic esters in excellent yield in a shorter reaction time with exclusive formation of the trans-isomer. The method was further extended successfully for styrenes.

Keywords:

• Catalyst-free
• N,N-dibromo-p-toluenesulfonamide (TsNBr₂)
• epoxidation
• epoxide
• olefin
• styrene
• α,β-unsaturated carbonyl compounds

ACKNOWLEDGMENT

Financial support from the Department of Science and Technology (Grant No. SR/S1/RFPC-07/2006) is gratefully acknowledged.

Notes

^a Reaction conditions: ethyl cinnamate (1.1 mmol), MeCN (4 mL), H₂O (1 mL), TsNBr₂ (1.2 mmol), K₂CO₃ (1.5 mmol), room temperature.

^b Isolated yield after chromatographic purifications.