Catalytic asymmetric Michael reactions of dibenzyl malonate to α,β-unsaturated N-acylpyrroles using a La(O-iPr)3/Ph-linked-BINOL complex |
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Authors: | So-Young Park Masakatsu Shibasaki |
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Institution: | Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan |
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Abstract: | Catalytic asymmetric Michael reactions of a malonate to acyclic α,β-unsaturated N-acylpyrroles as ester equivalent acceptors are described. A La(O-iPr)3/(S,S)-linked-BINOL complex, which is suitable for Michael addition to cyclic enones, is not suitable for acyclic α,β-unsaturated N-acylpyrroles. A new (S,S)-Ph-linked-BINOL chiral ligand was developed to improve enantioselectivity, and a La(O-iPr)3/(S,S)-Ph-linked-BINOL complex with the addition of HFIP afforded Michael adducts in good yield and enantioselectivity (up to 96% ee). |
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Keywords: | Asymmetric catalysis Lanthanide Linked-BINOL Michael reaction |
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