Application of recyclable ionic liquid-supported imidazolidinone catalyst in enantioselective Diels–Alder reactions

The application of ionic liquid-supported imidazolidinone catalyst I in enantioselective Diels–Alder reactions was investigated. The Diels–Alder reactions involving α,β-unsaturated aldehydes and cyclopentadiene proceeded efficiently in the presence of catalyst I to provide the desired products in moderate to good yields with good to excellent enantioselectivities. Especially noteworthy, catalyst I can be recovered and reused for up to five runs while maintaining its high catalytic activity.