Cross-linked basic nanogel; robust heterogeneous organocalayst

•A strong basic heterogeneous organocatalyst was synthesized.•The poly(ionic liquid) nanogel was used as catalyst for multi-component reaction.•Catalyst has high loading level of hydroxide ions.•Catalyst was recycled many times without any significant loss of catalyst activity.

A novel basic poly(ionic liquid) (PIL) was synthesized by miniemulsion polymerization of ionic liquid monomer 1-ethyl-3-vinylimidazolium bromide [EVim][Br] which was cross-linked by ionic liquid cross-linker 1,4-butanediyl-3,3′-bis-l-vinylimidazolium dibromide (BVD). Exchange of bromide anions in PIL nanogel with hydroxide, produced a supported basic ionic liquid catalyst. The catalytic performances of PIL nanogel with a size of about 200 nm was evaluated in the synthesis of 4H-benzo[b]pyrans by multi-component reaction in water. The present protocol represents a simple, ecologically safe and cost-effective route to synthesize 4H-benzo[b]pyrans with high products yield.