Substituent effects in the aliphatic Claisen rearrangement of substituted (1-methyl-3-oxahexa-1,5-dienyl)amines: synthesis of substituted 2-aminopent-4-enals. Alternative [1,3]-sigmatropic shifts in related aromatic systems
Alkyne Aminopalladation/Heck and Suzuki Cascades: An Approach to Tetrasubstituted Enamines
作者:Finn J. Geffers、Florens R. Kurth、Peter G. Jones、Daniel B. Werz
DOI:10.1002/chem.202103567
日期:2021.10.25
Internal alkynes have been used in combination with tosylamides and the Narasaka leaving group to form tetra(hetero)substituted enamines in an aminopalladationcascade reaction. The cascade was terminated either intramolecularly by a Heck reaction or intermolecularly in a Suzuki-type reaction with a boronic acid.
Rearrangements of silyl- and stannyl-substituted diallyl ethers: competition between the allyl-vinyl ether rearrangement and the [2,3] Wittig sigmatropic rearrangement
作者:T.N. Mitchell、F. Gießelmann、K. Kwetkat
DOI:10.1016/0022-328x(94)05307-w
日期:1995.5
Diallyl ethers containing two trimethylstannyl moieties or one triorganostannyl and one trimetyylsilyl moiety attached to the olefinic carbon atoms of one allyl group can undergo either an allyl-vinyl etherrearrangement or a [2,3] Wittig sigmatropic rearrangement when treated with a strong non-nucleophilic base. While the use of lithium diisopropylamide favours the Wittigrearrangement, lithium diethylamide
[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
Catalytic and Oxidative Methoxymercuration of Terminal Alkynes: Syntheses of 2-Methoxy-1-alkenes and 2-Methoxy-acrolein Acetals
作者:José Barluenga、Fernando Aznar、Miguel Bayod
DOI:10.1055/s-1988-27495
日期:——
2-Methoxy-1-alkenes 2 are easily obtained by reaction of a variety of 1-alkynes with an excess of methanol in the presence of triethylamine and catalytic amounts of mercury(II) chloride. By changing the molar ratio of the reagents and increasing the reaction time, propargyl ethers undergo a further oxidative process to give the 2-methoxyacrolein acetals 3.
Generation of α‐Boryl Radicals by H
<sup>.</sup>
Transfer and their Use in Cycloisomerizations
作者:Shicheng Shi、Farbod Salahi、Hunter B. Vibbert、Maleeha Rahman、Scott A. Snyder、Jack R. Norton
DOI:10.1002/anie.202107665
日期:2021.10.11
Carbon-centered radicals can be stabilized by delocalization of their spin density into the vacant p orbital of a boron substituent. α-Vinyl boronates, in particular pinacol (Bpin) derivatives, are excellent hydrogen atom acceptors. Under H2 , in the presence of a cobaloxime catalyst, they generate α-boryl radicals; these species can undergo 5-exo radical cyclizations if appropriate double bond acceptors
以碳为中心的自由基可以通过将其自旋密度离域到硼取代基的空 p 轨道中来稳定。α-乙烯基硼酸酯,特别是频哪醇(Bpin)衍生物,是优异的氢原子受体。在H2下,在钴肟催化剂存在下,它们生成α-硼基自由基;如果存在适当的双键受体,这些物质可以进行 5-exo 自由基环化,从而在 Bpin 上形成带有叔取代基的密集官能化杂环。该反应表现出良好的官能团耐受性和广泛的范围,所得硼酸酯产物可以转化为其他有用的官能团。