Sonogashira Reaction of Aryl and Heteroaryl Halides with Terminal Alkynes Catalyzed by a Highly Efficient and Recyclable Nanosized MCM-41 Anchored Palladium Bipyridyl Complex
A heterogeneous catalyst, nanosized MCM-41-Pd, was used to catalyze the Sonogashira coupling of aryl and heteroaryl halides with terminal alkynes in the presence of CuI and triphenylphosphine. The coupling products were obtained in high yields using low Pd loadings to 0.01 mol%, and the nanosized MCM-41-Pd catalyst was recovered by centrifugation of the reaction solution and re-used in further runs without significant loss of reactivity.
propargyl carbonates have been developed by using two O-containing functional groups as the traceless assisting groups (AGs). The experimental investigations together with the density functional theory (DFT) calculations revealed that this transformation involves the free OH-directed cleavage of one terminal C–H bond of the alkenyl moiety and regioselective alkyne insertion, followed by OBoc-promoted intramolecular
Anionic N-heterocyclic carbenes derived from sydnone imines such as molsidomine. Trapping reactions with selenium, palladium, and gold
作者:Tyll Freese、Ana-Luiza Lücke、Catharina A.S. Schmidt、Mika Polamo、Martin Nieger、Jan C. Namyslo、Andreas Schmidt
DOI:10.1016/j.tet.2017.07.032
日期:2017.9
The sydnone imines Molsidomine and 5-(benzoylimino)-3-(2-methoxyphenyl)-1,2,3-oxadiazolium-2-ide gave anionic N-heterocyclic carbenes on deprotonation at C4 which were trapped as methylated selenium adducts, gold complexes (X-ray analysis) as well as palladium complexes (X-ray analysis). The 13C NMR resonance frequencies of the carbene carbon atom are extremely shifted upfield and appear at δ = 142
sydnone亚胺的Molsidomine和5-(苯甲酰亚氨基)-3-(2-甲氧基苯基)-1,2,3-恶二唑-2-胺在C4脱质子化后得到阴离子N-杂环卡宾,以甲基化硒加合物,金配合物的形式被捕集(X射线分析)以及钯配合物(X射线分析)。卡宾碳原子的13 C NMR共振频率向高场偏移,并且出现在δ = 142.1 ppm(莫西多明卡宾)和δ = 159.8 ppm(亚砜亚胺卡宾)上。Pd配合物在Suzuki-Miyaura和Sonogashira-Hagihara交叉偶联反应中用作催化剂。
A mesoionic bis(Py-tzNHC) palladium(<scp>ii</scp>) complex catalyses “green” Sonogashira reaction through an unprecedented mechanism
A chelating ligand with one pyridine donor and one mesoionic carbene donor forms a novel type of cationic bis-carbene palladium complex that performs excellently in Sonogashira cross-coupling under green conditions.
Thermal Behavior of Diynes with Formally Conjugated Heteroaromatic Sidegroups
作者:Abhijit Sarkar、Satya S. Talwar
DOI:10.1246/bcsj.72.859
日期:1999.4
Diynes with heteroaromatic sidegroups directly linked to the acetylenic backbone were found to show liquid crystalline behaviour upon heating. Thus, 1,4-di(2-thienyl)-1,3-butadiyne, 1,4-di(3-thienyl)-1,3-butadiyne, 1,4-di(3-benzo[b]thienyl)-1,3-butadiyne, 1-(3-quinolyl)-4-(2-thienyl)-1,3-butadiyne, 1-(3-quinolyl)-4-(3-thienyl)-1,3-butadiyne, and 5-(2-thienyl)-2,4-pentadiyne-1-ol were investigated for their thermal behavior. These diynes also underwent polymerization in their liquid crystalline state, although the polymers so formed did not show liquid crystalline behavior. It was found that the S-atom of the heteroaromatic moieties tends to play a role in making the diynes show liquid crystalline behavior. Differential scanning calorimetry, thermogravimetric analysis and hot stage microscopy were used to investigate the liquid crystalline nature of the diynes. All of them showed a nematic liquid crystalline phase upon annealing, whereas smectic phase was totally absent.