Polyelectrolyte-catalyzed Diels–Alder reactions

Imidazolium-based poly(ionic liquids) bearing bromide and bis(trifluoromethane)sulfonimide as counteranions [poly(ViEIm)Br and poly(ViEIm)NTf2] derived from reversible addition fragmentation chain transfer (RAFT) polymerization techniques are used in polymer-assisted solution phase Diels–Alder reactions between isoprene and a variety of dienophiles. With 5 mol% loading, these polyelectrolytes exhibit very good catalytic activity toward Diels–Alder reaction with quantitative yields within 30 min at room temperature. These polyelectrolyte-catalyzed reactions resulted in good para/meta-like product ratios. Here, the coordination nature of the positively charged imidazolium groups in polyelectrolyte with dienophiles plays a key role in catalyst activity and selectivity. These polyelectrolytes were reused for 4 cycles without a significant loss in their catalytic activity and selectivity.