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

Abstract

Abstract The 1,4‐addition of alkylmagnesium chlorides to conjugated N ‐enoylsultams and subsequent ‘enolate trapping’ with aq. NH 4 Cl 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 .