2-Halogenoimidazolium Salt Catalyzed Aza-Diels–Alder Reaction through Halogen-Bond Formation
摘要:
2-Halogenoimidazolium salts are found to catalyze aza-Diels-Alder reaction of aldimines with Danishefsky diene in an efficient manner. Comparative studies and titration experiments support the formation of halogen bonding between imines and catalysts.
基于Chan-Lam交叉偶联反应,开发了一种基于使用稳定铜(I)源的现成Cu 2 S / TMEDA系统的催化剂。用1 H-苯并[ d ]咪唑-2(3 H)-1,1 H-苯并[ d ]咪唑和1 H-咪唑以及缺电子,富电子和在室温下,在大气氧的存在下,对空间需求量高的硼酸,以中等至极好的收率得到交叉偶联的产物。另外,1 H-苯并[ d]的偶联反应]咪唑与几种频哪醇或新戊二醇硼酸酯表明该催化剂的进一步潜力。反应条件容许羟基和溴官能团。该催化体系还能够由伯脂族胺合成单-N-取代的苯胺。但是,仲胺和芳族胺的两种模型化合物哌啶和苯胺不会反应。两个空间要求的产品与受限Ç N键的旋转,通过将合成的Ñ 1的-arylation ħ -苯并[ d ]咪唑-2(3 H ^) -酮与ö-甲苯磺酸,能够确认由Chan-Lam交叉偶联反应制得的阻转异构体。此外,已经报道了一锅Chan-Lam和Suzuki-Miyaura反应的例子。
A Multistage Halogen Bond Catalyzed Strain-Release Glycosylation Unravels New Hedgehog Signaling Inhibitors
作者:Chunfa Xu、Charles C. J. Loh
DOI:10.1021/jacs.9b00040
日期:2019.4.3
(XB) has recently emerged as a promising noncovalent activation mode that can be employed in catalysis. However, methodologies utilizing XB remain rare, and the hydrogen-bonding (HB) catalysis congeners are more widespread in comparison. Herein, we demonstrate a remarkable case whereby employment of XB catalysis in strain-release glycosylation generates O, N-glycosides in excellent anomeric selectivity
Three new ruthenium(II) complexes containing an N-heterocycliccarbene (NHC) ligand (RuNHC) have been successfully synthesized and proved to be efficient near-infrared (NIR) ECL (electrogenerated chemiluminescence) luminophores. In addition to the advantages of the lower-charge main motif (+1), the much lower oxidation potentials, and the longer metal to ligand charge transfer (MLCT) absorption bands
Using a halogen bond (XB) donor and Schreiner's thiourea as cooperative catalysts, various amides, including the asparagine residues of several peptides, were directly coupled with glycosyl trichloroacetimidates to give unique N‐acylorthoamides in good yields. Synthetic applications of N‐acylorthoamides, including rearrangement to the corresponding β‐N‐glycoside, were also demonstrated.
The direct 2-deoxyglycosylation of nucleophiles with glycals leads to biologically and pharmacologically important 2-deoxysugar compounds. Although the direct addition of hydroxyl and sulfonamide groups have been well developed, the direct 2-deoxyglycosylation of amide groups has not been reported to date. Herein, we show the first direct 2-deoxyglycosylation of amide groups using a newly designed
Bifurcated Nickel-Catalyzed Functionalizations: Heteroarene C−H Activation with Allenes
作者:Sachiyo Nakanowatari、Thomas Müller、João C. A. Oliveira、Lutz Ackermann
DOI:10.1002/anie.201709087
日期:2017.12.11
A unified strategy for nickel(0)‐catalyzed C−H allylations, alkenylations, and dienylations has been realized through versatile hydroarylations of allenes with ample scope. Thus, an inexpensive nickel catalyst modified with a N‐heterocyclic carbene ligand enabled the direct transformation of C−H bonds of biologically relevant imidazole and purine derivatives with full control of regio‐ and chemoselectivity