在含水介质中研究了镁介导的Barbier-Grignard型醛与烷基卤化物的烷基化反应。用THF或水作为反应溶剂,芳族醛与烯丙基卤的反应非常有效,但是在THF /水的混合物中效果较差。已经发现,镁与烯丙基溴和碘的醛介导的烯丙基化在0.1 N HCl或0.1 N NH(4)Cl水溶液中有效进行。芳族醛在脂肪族醛的存在下发生化学选择性反应。当脂族和芳族醛官能团同时存在于同一分子中时,也观察到排他选择性。在不存在烯丙基卤的情况下,醛和酮与镁在0.1 N NH(4)Cl水溶液中反应形成高产率的相应频哪醇偶联产物。频哪醇反应的有效性受到羰基周围空间环境的强烈影响。脂肪醛和简单的烷基卤化物在用于烷基化或频哪醇偶联反应的反应条件下呈惰性。
Reaction of aromatic aldehydes and ketones with ytterbium metal gives the corresponding pinacols in high yields. Cross-coupling reaction of benzophenone with other carbonyl compounds to produce unsymmetrical pinacols is also described.
It was firstly found that the Rieke Ni generated in situ was able to promote the pinacol coupling of various carbonyls efficiently. Based on this information, another catalytically effective, cheaper and more convenient NiCl2(Cat.)/Mg/TMSCl system was designed and developed further successfully. The interesting single-electron transfer (SET) mechanisms for the coupling reactions were proposed. Additionally
We present herein an unprecedented diastereoconvergent synthesis of vicinal diamines from diols through an economical, redox-neutral process. Under cooperative ruthenium and Lewis acid catalysis, readily available anilines and 1,2-diols (as a mixture of diastereomers) couple to forge two C−N bonds in an efficient and diastereoselective fashion. By identifying an effective chiral iridium/phosphoric
Ring Closing Metathesis Approach for the Synthesis of <i>o</i>
-Terphenyl Derivatives
作者:Shilpi Karmakar、Tirtha Mandal、Jyotirmayee Dash
DOI:10.1002/ejoc.201900988
日期:2019.9.15
A synthetic method for o‐terphenyls from benzils is reported usingringclosingmetathesis (RCM) as the key step. o‐Terphenyls with halogen substituents are synthesized that can be further functionalized by cross coupling reactions. The synthesis of triphenylenes demonstrates the synthetic utility of the approach.
Photoelectrochemistry on TiO2/Ti anodes as a tool to increase the knowledge about some photo-oxidation mechanisms in CH3CN
作者:Marta Bettoni、Cesare Rol、Giovanni V. Sebastiani
DOI:10.1002/poc.1303
日期:2008.3
TiO2 (rutile)/Ti anodes, further mechanistic information has been obtained regarding the TiO2 photosensitized oxidation of benzylic alcohols, ethers and 1,2-diols in CH3CN. In deaerated medium, two electrons are captured by the semiconductor from all the considered substrates (one from the substrate, the second from the intermediate benzylic radical). In contrast, in aerated CH3CN, the number of TiO2-captured