نتایج جستجو برای: alkynes
تعداد نتایج: 3647 فیلتر نتایج به سال:
Abstract: A rhenium complex, [ReBr(CO)3(thf)]2, catalyzed insertion of terminal alkynes into a C–H bond of active methylene sites of 1,3-dicarbonyl compounds. When a catalytic amount of isocyanide or molecular sieves was added to the reaction mixture, the reaction course changed markedly, and insertion of alkynes into a C–C single bond between αand β-positions of cyclic and acyclic β-keto ester...
The direct hydroamination of alkynes driven by visible light can be achieved in high yield and selectivity at ambient temperature using supported gold nanoparticles (AuNPs) as photocatalysts. Aniline molecules interact with visible light activated AuNPs meanwhile alkynes could be activated at active sites on the support. The findings reveal a new green approach for synthesis of fine organic com...
A new, simple and straight-forward protocol for direct carboxylation of terminal alkynes has been developed using Cu-montmorillonite K10 clay as a heterogeneous catalyst and CO2 as the C1 carbon feedstock. Also coupling of terminal alkynes with CO2 (1 atm) in the presence of alkyl halides has been achieved under the same reaction conditions, thereby providing access to a variety of functionaliz...
Indium(III) halides catalyze efficiently the intramolecular hydroarylation (IMHA) of aryl propargyl ethers. The reaction proceeds regioselectively with terminal and internal alkynes bearing electron-rich and electron-deficient substituents in the benzenes and alkynes affording only the 6-endo dig cyclization product. Additionally, a sequential indium-catalyzed IMHA and palladium-catalyzed Sonog...
Separation of the enantiomers of new chiral alkynes in strategic syntheses and bioorthogonal studies is always problematic. The chiral column high-performance liquid chromatography (HPLC) method in general could not be directly used to resolve such substrates, since the differentiation of the alkyne segment with the other alkane/alkene segment is not significant in the stationary phase, and the...
Nucleophilic addition to alkynes represents an attractive approach to the synthesis of olefins. Obstacles to this strategy include the low reactivity of alkynes toward many organometallic reagents and difficulties associated with controlling the regioselectivity of addition. Here we demonstrate that Fe(III) salts are effective precatalysts for the carbometalation of alkynes. Primary and seconda...
This work represents our initial effort in identifying azide/alkyne pairs for optimal reactivity in copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions. In previous works, we have identified chelating azides, in particular 2-picolyl azide, as "privileged" azide substrates with high CuAAC reactivity. In the current work, two types of alkynes are shown to undergo rapid CuAAC reactions u...
In recent years, considerable effort has been devoted to develop methodologies which reduce multi-step transformations into one-step tandem processes. In this regard, the use of multifunctional catalysts, which promote sequential reaction steps without additional requirement of additives and/or co-catalysts, provides an effective way while taking care of two most basic challenges faced by a syn...
High concentrations of acetylene (10 to 50% [vol/vol] gas phase) were required to inhibit the growth of Burkholderia cepacia G4 on toluene, while 1% (vol/vol) (gas phase) propyne or 1-butyne completely inhibited growth. Low concentrations of longer-chain alkynes (C5 to C10) were also effective inhibitors of toluene-dependent growth, and 2- and 3-alkynes were more potent inhibitors than their 1-...
The synthesis of a novel class of 2-oxoindolin-3-ylidene-(1-arylhydrazinyl)-2-aryl(alkyl)ethylidene derivativesvia a copper-catalyzed tandem reaction of isatin, arylhydrazines, sulfonyl azides and terminal alkynes is described.
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