N‐Heterocyclic Carbenes Supported on Vinylic Addition Polynorbornene: A Recyclable and Recoverable Organocatalyst

Abstract

Abstract A bromoalkyl functionalized vinylic addition polynorbornene has been used as an inert new scaffold to support imidazolium salts by straightforward nucleophilic substitution using different imidazoles ImR (R=Me, mesityl, 2,6‐ i Pr 2 C 6 H 3 ). These polymers, VA‐PNB‐(CH 2 ) 4 ImRBr, are precursors of N‐heterocyclic carbenes which are useful as heterogeneous organocatalysts. The polymeric carbenes have been tested in two model reactions: The synthesis of saturated esters from α,β‐unsaturated aldehydes and the conjugate umpolung reaction of α,β‐unsaturated aldehydes for the synthesis of γ‐butyrolactones. The supported catalyst (R=mesityl) is fully recyclable and can be recovered as an imidazolium salt and stored for further use.