Recyclable Asymmetric Cyclization in Ionic Liquid Catalyzed by an Amino Acid, Leading to a Wieland-Miescher Ketone Analogue

A procedure for recyclable asymmetric cyclization leading to optically active Wieland-Miescher ketone analogue has been developed employing d-phenylalanine and d-CSA in [hmim]PF6 and dimethylimidazolidinone in 81% chemical yield and 74% enantiomeric excess in average after five uses. A Hajos-Wiechert ketone analogue was also synthesized in a similar manner.