Highly Enantioselective Diels–Alder Reaction Catalyzed by Chiral Imidazolidinone

Abstract

New chiral imidazolidinone with an indole group was synthesized and used to catalyze the Diels–Alder reaction of α,β-unsaturated aldehyde with diene. High enantiomeric excesses and good yields were obtained. The reaction media were also surveyed. The best result in terms of enantioselectivity was achieved using acrolein and 2,3-dimethylbutdiene (up to 95% ee) in CH₃OH/H₂O.

Keywords:

• Catalyst
• Diels–Alder reaction
• imidazolidinone
• α,β-unsaturated aldehyde

ACKNOWLEDGMENTS

We are indebted to Xu Xu and Shuping Luo for performing the GLC analyses. We are also grateful to the Key Subject of Industrial Catalysis for financial support.

Notes

^a Isolated yield.

^b Product ratios determined by GLC using an RTX-13100 column.

^c Absolute and relative configurations were determined by correlation to the literature.^{[ 4 , 6 , 7 ]}.

^d Using 5.0 mol% catalyst.

^a Enantiomeric excess and exo/endo determined by chiral GLC analysis (RTX-13100 column).

^b Isolated yield.

^a Isolated yield.

^b Product ratios determined by GLC using an RTX-13100 column.

^c Product ratios determined by HPLC using an AS-H column.

^d Absolute configuration of exo.

^e Absolute configuration of para.

^f Absolute and relative configurations were determined by correlation to the literature.^{[ 4 , 6 , 7 ]}