Synthesis of Ethyl (S)-3-(1-Methyl-2-Oxo-Cyclohexyl)-2-Oxopropanoate Through Stereoselective Michael Addition

A practical four-step sequence for the synthesis of α,δ-dioxoesters with high enantiomeric excess was developed. It makes use of a regio- and stereoselective Michael addition of a chiral ketimine to ethyl 2-(phenylthio)-2-propenoate as a key transformation. The synthetic elaboration of the Michael adduct provides the new ethyl 3-(1-methyl-2-oxo-cyclohexyl)-2-oxopropanoate, bearing a quaternary stereocenter with 95% ee and high yield.