The asymmetric Michael reaction between 2-thiosubstituted chiral imines/secondary enamines derived from (S)-1-phenylethylamine and electrophilic alkenes (methyl acrylate, MVK) was investigated. 2-Phenylthio derivatives furnished the expected Michael adducts with excellent ee. By contrast, an in situ elimination of p-toluenesulfenic acid took place when using the p-toluenesulfinyl analogs.
