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New DABCO‐based chiral ionic liquids were synthesized and evaluated in asymmetric Diels–Alder reaction of cyclopentadiene with α,β‐unsaturated aldehydes or 4‐phenyl‐3‐buten‐2‐one. Chiral ionic liquid of modified MacMillan catalyst having a DABCO cation and hexafluorophosphate anion acts as organocatalyst (5 mol%) for the Diels–Alder reaction of crotonaldehyde and cyclopentadiene producing 98% of the product and 87% ee (endo) in CH3CN/H2O (95/5) at 25°C in 2 h. The scope and limitations of the catalysis were also studied by using cyclopentadiene and α,β‐unsaturated aldehydes, and the Diels–Alder products were obtained in 18%–92% yields with 68%–93% ee. The catalyst was recycled and reused up to 6 cycles with a slight drop in ee and conversion of the product. [ABSTRACT FROM AUTHOR]

Imidazolidin‐4‐one is used as a recoverable organocatalyst for the asymmetric Diels‐Alder reaction in the presence of catalytic amount of dicationic ionic liquid and trifluoroacetic acid as a co‐catalyst. The Diels‐Alder reaction between model substrate cyclopentadiene and crotonaldehyde gave the product in 95% conversion and 87% ee of the endo‐product. The catalyst was shown better reusability when the 20 mol% of dicationic ionic liquid was used and catalyst was reused upto 5 cycles, conversion remains upto 3 recycles but ee of endo‐9 was slightly droped. [ABSTRACT FROM AUTHOR]