Synthesis of 1,3-Diynes via Cadiot–Chodkiewicz Coupling of Volatile, in Situ Generated Bromoalkynes
作者:Phil C. Knutson、Haleigh E. Fredericks、Eric M. Ferreira
DOI:10.1021/acs.orglett.8b02975
日期:2018.11.2
A convenient Cadiot–Chodkiewicz protocol that facilitates the use of low molecular weight alkyne coupling partners is described. The method entails an in situ elimination from a dibromoolefin precursor and immediate subjection to copper-catalyzed conditions, circumventing the hazards of volatile brominated alkynes. The scope of this method is described, and the internal 1,3-diyne products are preliminarily
Synthesis and spectral properties of 1,4- and 1,3-pentadiynes
作者:H. Taniguchi、I.M. Mathai、S.I. Miller
DOI:10.1016/0040-4020(66)80058-3
日期:1966.1
to 1,5-diphenyl-1,4-pentadiyne have now been shown to give 1,4-diphenylbutadiyne. Spectral properties, NMR, IR, UV, are given for both series. Shoolery's rule is found useful in predicting the chemical shift, τ(CH2),for these and other kinds of acetylenic compounds. On the basis of their UV spectra, one can say that in the 1,4-diynes there is little, if any, conjugation “through” the internal methylene
Given the powerful potential of chiral-at-silicon chemistry, enantioselective synthesis of Si-stereogenic centers has attracted substantial research interest in recent years. However, the catalytic asymmetric synthesis of Si-stereogenic organosilicon compounds remains an appealing venture and is a challenging subject because of the difficulty in achieving high reactivity and stereoselectivity for “silicon-center”
鉴于硅手性化学的巨大潜力,近年来,硅手性中心的对映选择性合成引起了广泛的研究兴趣。然而,Si-立体有机硅化合物的催化不对称合成仍然是一个有吸引力的冒险,并且由于难以实现“硅中心”转化的高反应性和立体选择性,因此是一个具有挑战性的课题。在此,我们公开了一种高度对映选择性钯催化的 1,3-二炔与二氢硅烷的氢化硅烷化反应,这使得能够以良好的收率和优异的 ee(高达 > 99%)通过去对称化。该反应中不同寻常的立体选择性是通过精确控制新开发的手性配体的空间位阻和电子效应实现的,从而产生范围广泛的手性硅烷和带有 Si 手性中心的含 Si 聚合物,否则很难获得. 高对映选择性的关键依赖于催化剂聚集诱导的非共价相互作用,这对 Si-H 键的活化和对映选择性的增强产生了显着的积极影响,其中钯/P-配体络合物被证明是空气-在此反应中稳定且对水分不敏感。