Stereoselective Conjugate Addition-Enamination of α-Linear N - tert -Butanesulfinyl Ketimines with Nitroolefins.

N -Sulfinyl metalloenamines, generated by deprotonating α-linear N - tert -butanesulfinyl ketimines, reacted with nitroalkenes via stereoselective conjugate addition to give Michael adducts with opposite stereochemistry to that obtained using α-branched sulfinylketimines. In the presence of excess base (2.5 equiv t -BuOK), the adducts derived from α-linear ketimines were further stereoselectively deprotonated to afford the corresponding kinetically favorable N -sulfinyl (Z)-enamine derivatives in good yields with good stereoselectivities. A reaction model was proposed to rationalize the observed stereochemistry. [ABSTRACT FROM AUTHOR]