145. Asymmetric Induction on Copper(I) Chloride catalyzed 1,4-addition of alkylmagnesium chlorides to α,β-disubstituted (E)-enoylsultams and subsequent protonation
     Oppolzer, W.; Kingma, A. J.
     Helv. Chim. Acta 1989, 72, 1337-1345

Successive treatment of conjugated N-enoylsultams 2 with alkyl Grignard reagents/CuCl and aq. NH₄Cl solution generated selectively two stereogenic centers at C(α) and C(β) providing, after flash chromatography and crystallization, acylsultams 5 in high purity. Mild cleavage afforded the recovered sultam auxiliary 1 and enantiomerically pure carboxylic acids 7.

DOI : 10.1002/hlca.19890720622 

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