142. Asymmetric 1,4-additions of Gilman reagents to α,β-disubstituted (e)-enoylsultams / “enolate” protonations
     Oppolzer, W.; Kingma, A. J.; Poli, G.
     Tetrahedron 1989, 45, 479-488

Successive treatment of (E)-Cα,Cβ-disubstltuted N-enoyl sultams 6 and 13 with organocopper reagents (Me₂CuLi, (CH₂?CH)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 two new stereogenic centers. The postulated reaction topology is supported via acetylatlon of the transient “nolate” (22 → 23) and compared with that of the related organomagnesium- addition/protonation sequence.

DOI : 10.1016/0040-4020(89)80075-4 

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