Contrasting Facial Selectivity of a Squaramide‐Tagged Proline in the Asymmetric Michael Addition of Ketones to Maleimides

Abstract A squaramide moiety was introduced at the C‐4 position of proline to afford an organocatalyst that served as a stereocontrol element to promote the asymmetric Michael addition of cyclic ketones to maleimides. A variety of chiral succinimides were obtained by the conjugate addition in 84–98% yield accompanied by 58–96% enantioselectivity. The results also include an interesting contrast in the facial selectivity observed with cyclohexanones and cycloheptanones, whereas an asymmetric desymmetrization of 4‐alkyl cyclohexanones was also achieved using the transformation.