Stereochimie de quelques reactions entre aldehydes et reactifs de Grignard satures et allyliques
作者:H. Felkin、Y. Gault、G. Roussi
DOI:10.1016/s0040-4020(01)92953-9
日期:1970.1
γ-dimethylallyl magnesium bromides) and secondary alkyl [s-butyl magnesium bromide and (1,2-dimethylpropyl) magnesium chloride] Grignardreagents to form pairs of diastereoisomeric alcohols R′—CHMeCHOH—R (R′ = CH2CH, CH2CMe, Et and iPr, respectively). The reactions involving the secondary alkylGrignardreagents are not stereoselective; those involving the allylic Grignardreagents show some stereoselectivity
[2,3]-Wittig sigmatropic rearrangement of crotyl propargyl ether system. An emerging tool for control of acyclic stereochemistry
作者:Kōichi Mikami、Ken-Ichi Azuma、Takeshi Nakai
DOI:10.1016/0040-4020(84)80013-7
日期:1984.1
The [2,3]-Wittigrearrangement of properly designated (E)- and (Z)-crotyl propargylether system has been shown to exhibit a remarkably high degree of threo- and erythro -selection, respectively, and the stereochemical outcomes are discussed on mechanistic grounds. Some useful transformations of the rearrangement product are also described within the context of the formal total synthesis of (±)-oudemansin
significantly by the steric effect of bulky groups. However, the influence of steric alkylchain length has not been studied for the diastereoselectivity. In this work, we present a new strategy for the racemic synthesis of β-methyl alcohols to obtain various diastereomer ratios using the Felkin–Anh model. The addition of alkyl Grignard reagents to α-methyl aldehydes afforded diastereomer ratios of threo/erythro