PTC-Catalyzed Enantioselective Michael Addition Reactions

The glycinate Schiff base of benzophenone 17 was also shown to be a suitable Michael donor for the asymmetric 1,6-addition to the activated dienes 44 having ketones, esters, and sulfones as substituents. Using Corey s phase-transfer catalyst, 16, the corresponding allylated products 47 were obtained as a single E-isomer with high enantioselectivity (from 92 to 98% ee). The synthetic utility of this reaction 

9 Cinchona-Catalyzed Nucleophilic Conjugate Addition to Electron-Deficient C—C Double Bonds 

However, the use of the glycinate Schiffbase imine (17) as a Michael donor provided low to moderate enantioselectivity (60-88% ee). 

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