Asymmetric Induction on Copper(I) Chloride catalyzed 1,4-addition of alkylmagnesium chlorides to ?, ?-disubstituted (E)-enoylsultams and subsequent protonation
作者:Wolfgang Oppolzer、Arend J. Kingma
DOI:10.1002/hlca.19890720622
日期:1989.9.20
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.
Asymmetric 1,4-additions of gilman reagents to α,β - disubstitoted (e)-enoylsultams / “enolate” protonations
作者:Wolfgang Oppolzer、Arend J. Kingma、Giovanni Poli
DOI:10.1016/0040-4020(89)80075-4
日期:1989.1
Successive treatment of (E)-Cα,Cβ-disubstltuted N-enoyl sultams 6 and 13 with organocopper reagents (Me2CuLi, (CH2CH)2CuLi, Ph2CuLi in the presence of PBu3 or SCN−) and aq. NH4Cl gave products 7 and 14. respectivety, with good to excellent stereoface differentiation at Cβ and Cα. Crystallization and mild saponification 7 → 11 and 14 → 15 furnished enantiomerically pure carboxylic acids containing