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Isothiourea-Catalyzed Enantioselective Michael Addition of Malonates to α,ß-Unsaturated Aryl Esters.
Org Lett
; 24(22): 4040-4045, 2022 Jun 10.
Article
in English
| MEDLINE
| ID: mdl-35652512
ABSTRACT
An enantioselective Michael addition of malonates to α,ß-unsaturated para-nitrophenyl esters was achieved using the Lewis basic isothiourea HyperBTM, giving excellent levels of product enantioselectivity (up to >99:1 enantiomeric ratio) in good yields and with complete regioselectivity (>20:1 regioselectivity ratio) in the presence of alternative (phenyl ketone and ethyl ester) Michael acceptors. Density functional theory calculations indicate that N-acylation is rate-limiting. This constitutes a rare example of a highly enantioselective addition of simple, readily available malonates to α,ß-unsaturated esters.