Abstract A mild and selective transition metal free protocol for the conversion of propargylic alcohols to cyclic and acyclic α, β-unsaturated enones via the Rupe rearrangement is reported. The method utilizes the Brønsted acidic ionic liquid [BMIM-SO 3 H][OTf] as catalyst and [BMIM][PF 6] as solvent and offers the potential for recycling and reuse of the IL solvent. The feasibility to synthesize bicyclic fused cyclopentenone derivatives via a Rupe→ Aldol ...