Formation of Quaternary Stereogenic Centers by Copper-Catalyzed Asymmetric Conjugate Addition Reactions of Alkenylaluminums to Trisubstituted Enones
作者:Daniel Müller、Alexandre Alexakis
DOI:10.1002/chem.201302856
日期:2013.11.4
undergo asymmetric copper‐catalyzedconjugateaddition (ACA) to β‐substituted enones allowing the formation of stereogenic all‐carbon quaternary centers. Phosphinamine–copper complexes proved to be particularly active and selective compared with phosphoramidite ligands. After extensive optimization, high enantioselectivities (up to 96 % ee) were obtained for the addition of alkenylalanes to β‐substituted
Reaction Rate and Isomer-Specific Product Branching Ratios of C<sub>2</sub>H + C<sub>4</sub>H<sub>8</sub>: 1-Butene, <i>cis</i>-2-Butene, <i>trans</i>-2-Butene, and Isobutene at 79 K
作者:Jordy Bouwman、Martin Fournier、Ian R. Sims、Stephen R. Leone、Kevin R. Wilson
DOI:10.1021/jp403637t
日期:2013.6.20
rate constants are (1.9 ± 0.5) × 10–10, (1.7 ± 0.5) × 10–10, (2.1 ± 0.7) × 10–10, and (1.8 ± 0.9) × 10–10 cm3 s–1 for the reaction of C2H with 1-butene, cis-2-butene, trans-2-butene, and isobutene, respectively. Bimolecular rate constants for 1-butene and isobutene compare well to values measured previously at 103 K using C2H chemiluminescence. Photoionization spectra of the reaction products are measured
在79 K的Laval喷嘴膨胀条件下,通过激光光解-真空紫外质谱法研究了C 2 H自由基与C 4 H 8异构体1-丁烯,顺式-2-丁烯,反式-2-丁烯和异丁烯的反应。通过在伪一级条件下测量反应产物种类的形成速率与反应物密度的函数,可以得到双分子反应速率常数。所述速率常数(1.9±0.5)×10 -10,(1.7±0.5)×10 -10,(2.1±0.7)×10 -10,和(1.8±0.9)×10 -10厘米3个小号-1为C 2的反应H分别与1-丁烯,顺式-2-丁烯,反式-2-丁烯和异丁烯一起。1-丁烯和异丁烯的双分子速率常数与先前使用C 2 H化学发光法在103 K下测得的值相比较。测量反应产物的光电离光谱,并将其拟合为贡献异构体的电离光谱。结合绝对电离截面,这些拟合可提供异构体拆分的产物分支馏分。C 2 H和1-丁烯之间的反应生成乙烯基乙炔形式的(65±10)%C 4 H 4和4-戊烯-1-炔形式的(35±10)%C
Gold-Catalyzed 1,4-Carbooxygenation of 3-En-1-ynamides with Allylic and Propargylic Alcohols<i>via</i>Non-Claisen Pathways
作者:Sovan Sundar Giri、Li-Hsuan Lin、Prakash Daulat Jadhav、Rai-Shung Liu
DOI:10.1002/adsc.201601092
日期:2017.2.20
Gold‐catalyzed1,4‐carbooxygenations of 3‐en‐1‐ynamides with allylic alcohols and propargylic alcohols yield α,β‐unsaturated amides through non‐Claisen pathways; the mechanisms involve ionization of the initial gold enol ethers to form C‐bound gold dienolates that capture allylic or propargylic cations to yield the observed products. Our 18O‐labeling experiments exclude a direct gold‐catalyzed allylation
Reactions of Cobaloxime Anions and/or Hydrides with Enynes as a New, General Route to 1,3- and 1,2-Dienylcobaloxime Complexes
作者:Heather L. Stokes、Mark E. Welker
DOI:10.1021/om960058f
日期:1996.5.28
A new method for the preparation of dienylcobaloxime complexes which involves reactions of cobaloxime anions and/or hydrides with enynes is reported. This new dienyl complex preparative method leads to cobalt-substituted 1,3- or 1,2-dienes depending on the enyne substitution pattern chosen. Subsequent Diels−Alder reactions of the 1,3-dienyl complexes and demetalation reactions of cobalt-substituted
作者:Gregory J. Hollingworth、Alexandre M. E. Richecoeur、Joseph Sweeney
DOI:10.1039/p19960002833
日期:——
The palladium-catalysed cross-coupling reaction of 4-tributylstannylfuran-2(5H)-one 3 with 1-iodo-4-methylpent-3-en-1-yne 4a gives the natural product cleviolide; from this substance may be prepared both (Z)- and (E)-isomers of scobinolide.