The 1,4-addition of alkylmagnesium chlorides to conjugated N-enoylsultams and subsequent ‘enolate trapping' with aq. NH4Cl or MeI/hexamethylphosphoric triamide generated centers of asymmetry at C(β) and/or at C(α) with good to excellent π-face defferentiation as demonstrated by the conversions 1→2, 1→4, and 8→9. This holds also for the regioselective 1,4-addition of EtMgC1 to a dienoylsultam (15→16). Reactive conformations 1≠, 8≠, 13, and 14 are postulated in agreement with X-ray evidence which also served for the structure determination of the product 9j.