Asymmetric Induction at C(β) and C(α) of N-Enoylsultams by Organomagnesium 1,4-Addition/Enolate Trapping

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 .