Conjugate Addition of a Silyl Ketene Acetal to α,β‐Unsaturated Lactones

Abstract

Conjugate addition of a silyl ketene acetal [Me₂C˭C (OMe)OSiMe₃] to α,β‐unsaturated lactones (namely, 5,6‐dihydro‐2H‐pyran‐2‐one, 2(5H)‐furanone as Michael acceptor) occurs efficiently at room temperature in the presence of a nucleophilic catalyst, tetra‐n‐butyl ammonium bibenzoate (TBABB), in THF as well as Lewis acid catalysts such as Yb(OTf)₃ and I₂ in CH₂Cl₂, giving the corresponding 1,4‐adducts in excellent yields.

Keywords:

• 1,4‐Addition
• Conjugate addition
• cyclic α,β‐unsaturated esters
• electrophile
• Lewis acid
• Michael acceptor
• Michael addition
• Mukaiyama–Michael addition
• O‐silylated ketene acetal
• nucleopilic catalyst

Acknowledgments

R. G. thanks CSIR, New Delhi, for a senior research fellowship.