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Publication 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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