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

N-Sulfinyl metalloenamines, generated by deprotonating alpha-linear N-tert-butariesulfinyl ketimines, reacted with nitroalkenes via stereoselective conjugate addition to give Michael adducts with opposite stereochemistry to that obtained using alpha-branched sulfinylketimines. in the presence of excess base (2.5 equiv t-BuOK), the adducts derived from alpha-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.

Automated summary

N-Sulfinyl metalloenamines, generated by deprotonating alpha-linear N-tert-butariesulfinyl ketimines, reacted with nitroalkenes via stereoselective conjugate addition to give Michael adducts with opposite stereochemistry. In the presence of excess base, the adducts derived from alpha-linear ketimines were further stereoselectively deprotonated to afford N-sulfinyl (Z)-enamine derivatives with good yields and stereoselectivities. A reaction model was proposed to rationalize the observed stereochemistry.