Direct difunctionalization of activated alkynes via domino oxidative benzylation/1,4-aryl migration/decarboxylation reactions under metal-free conditions

2016 ◽  
Vol 52 (15) ◽  
pp. 3175-3178 ◽  
Author(s):  
Tao Miao ◽  
Dong Xia ◽  
Yang Li ◽  
Pinhua Li ◽  
Lei Wang

The oxidative difunctionalization of aryl alkynoatesviaa tandem oxidative benzylation/1,4-aryl migration/decarboxylation to trisubstituted alkenes was developed under metal-free conditions.

2017 ◽  
Vol 19 (7) ◽  
pp. 1732-1739 ◽  
Author(s):  
Dong Xia ◽  
Yang Li ◽  
Tao Miao ◽  
Pinhua Li ◽  
Lei Wang

A visible-light-induced oxidative difunctionalization of activated alkenes with simple ethersviaselective C(sp3)–H bond cleavage and dual C–C bond formation was developed.


2021 ◽  
Author(s):  
Ting Han ◽  
Shusheng Chen ◽  
Xinnan Wang ◽  
Xinyao Fu ◽  
Haifei Wen ◽  
...  

The development of autonomous materials with desired performance and built-in visualizable sensing units is of great academic and industrial significance. Although a wide range of damage indication methods have been reported, the “turn-on” sensing mechanism by damaging events based on microcapsule systems, especially those relying on chemical reactions to elicit a chromogenic response, are still very limited. Herein, a facile and metal-free polymerization route with an interesting reaction-induced coloration effect is demonstrated. Under the catalysis of 1,4-diazabicyclo[2.2.2]octane (DABCO), the polymerizations of difunctional or trifunctional activated alkynes proceed very quickly at 0 oC in air. A series of polymers composed of stereoregular enyne structure (major unit) and divinyl ether structure (minor unit) are obtained. Both the catalyst and monomers are colorless while the polymerized products are deep-colored. This process can be applied for the damage visualization of polymers using the microencapsulation technique. Microcapsules containing the reactive alkyne monomer are prepared and mixed in a DABCO-dispersed polymer film. The mechanical damage of this composite film can be readily visualized once the reaction is initiated from the ruptured microcapsules. Moreover, the newly formed polymer automatically sealed the cracks with an additional protection function.


2019 ◽  
Vol 6 (7) ◽  
pp. 989-993 ◽  
Author(s):  
Arvind Kumar Yadav ◽  
Anup Kumar Sharma ◽  
Krishna Nand Singh

Metal-free γ-trifluoromethylation of Baylis–Hillman acetates is reported using Langlois’ reagent under visible light photoredox catalysis.


RSC Advances ◽  
2015 ◽  
Vol 5 (129) ◽  
pp. 106350-106354 ◽  
Author(s):  
Ping Wang ◽  
Zhongfeng Li ◽  
Shengli Cao ◽  
Honghua Rao

The first intermolecular addition reaction of aryloxyl radicals to CC bonds was disclosed, which can afford biologically important chromonsviaa PhNMe3I-catalyzed direct coupling of salicylaldehydes and activated internal alkynes in only one step.


Research ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Xianglong Hu ◽  
Xueqian Zhao ◽  
Benzhao He ◽  
Zheng Zhao ◽  
Zheng Zheng ◽  
...  

The efficient bioconjugation of functional groups/molecules to targeted matrix and bio-related species drives the great development of material science and biomedicine, while the dilemma of metal catalysis, uneasy premodification, and limited reaction efficiency in traditional bioconjugation has restricted the booming development to some extent. Here, we provide a strategy for metal-free click bioconjugation at diverse levels based on activated alkynes. As a proof-of-concept, the abundant native groups including amine, thiol, and hydroxyl groups can directly react with activated alkynes without any modification in the absence of metal catalysis. Through this strategy, high-efficient modification and potential functionalization can be achieved for natural polysaccharide, biocompatible polyethylene glycol (PEG), synthetic polymers, cell penetrating peptide, protein, fast whole-cell mapping, and even quick differentiation and staining of Gram-positive bacteria, etc. Therefore, current metal-free click bioconjugation strategy based on activated alkynes is promising for the development of quick fluorescence labeling and functional modification of many targets and can be widely applied towards the fabrication of complex biomaterials and future in vivo labeling and detection.


2018 ◽  
Author(s):  
Sharada Duddu. S ◽  
Sagar Arepally ◽  
Arumugavel Murugan ◽  
Mamata Ojha

<p>An organic dye photoredox-catalyzed oxidative C-C triple bond cleavage <i>via</i> hydroamination leading to oxamates at room temperature has been described. The key features of this transformation are the mild conditions, metal-free organic dye as photocatalyst, broad amines scope, and a tandem hydroamination-oxidative C-C triple bond cleavage. </p>


Author(s):  
George C. Ruben

The formation of shadows behind small particles has been thought to be a geometric process (GP) where the metal cap build up on the particle creates a shadow width the same size as or larger than the particle. This GP cannot explain why gold particle shadow widths are generally larger than the gold particle and may have no appreciable metal cap build up (fig. 1). Ruben and Telford have suggested that particle shadow widths are formed by the width dependent deflection of shadow metal (SM) lateral to and infront of the particle. The trajectory of the deflected SM is determined by the incoming shadow angle (45°). Since there can be up to 1.4 times (at 45°) more SM directly striking the particle than the film surface, a ridge of metal nuclei lateral to and infront of the particle can be formed. This ridge in turn can prevent some SM from directly landing in the metal free shadow area. However, the SM that does land in the shadow area (not blocked by the particle or its ridge) does not stick and apparently surface migrates into the SM film behind the particle.


Nanoscale ◽  
2020 ◽  
Vol 12 (15) ◽  
pp. 8065-8094 ◽  
Author(s):  
Xudong Wen ◽  
Jingqi Guan

Different kinds of electrocatalysts used in NRR electrocatalysis (including single atom catalysts, metal oxide catalysts, nanocomposite catalysts, and metal free catalysts) are introduced.


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