A highly diastereo- and enantioselective Michael addition reaction with respect to prochiral 3-substituted oxindoles and maleimides by a chiral bifunctional thiourea-tertiary amine catalyst was investigated for the first time. The corresponding adducts, containing a quaternary center at the C3-position of the oxindole as well as a vicinal tertiary center, were generally obtained in good to high yields (up to 92%) with high to excellent diastereo- (up to 99:1 dr) and enantioselectivities (up to 99% ee).
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Article Synopsis
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- The resulting allyl compounds feature both a tertiary carbon (C) stereocenter and a phosphorous (P) stereocenter, achieving high selectivity with over 20:1 ratios in diastereomers and enantiomers, along with 99% enantiomeric excess.
- A unique aspect is the ability to create all four P-containing stereoisomers in one reaction and the process is efficient, requiring only 3 minutes
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