On the Roles of Protic Solvents in Imidazolidinone-Catalyzed Transformations


  • The authors thank the EPSRC for financial support under grant reference EP/E018718/1, and the Mass Spectrometry Service, Swansea, for high-resolution spectra.


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Step by step: The effect of protic solvents on the rate and stereochemical outcome of the imidazolidinone-catalyzed Diels–Alder cycloaddition was rationalized. The following picture emerges: the solvent accelerates iminium ion formation (step 1), the Diels–Alder cycloaddition is reversible (step 2), and the solvent intercepts the iminium ion adduct (step 3).