Oxidation of alkynes using PdCl2/CuCl2 in PEG as a recyclable catalytic system: one-pot synthesis of quinoxalines

Chandrasekhar, S.; Reddy, Naredla Kesava; Kumar, Vemula Praveen

doi:10.1016/j.tetlet.2010.05.006

Cited by 71 publications

(21 citation statements)

References 28 publications

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“…The reaction was solvent‐dependent chemoselective reaction, affording two cyclized products selectively with the same substrate, short reaction time, operational simplicity, as well as available starting materials and non‐toxic catalysts (Route i). Oxidation of alkynes efficiently using the catalytic amount of PdCl 2 and CuCl 2 in PEG‐400 in the presence of water have been reported by Chandrasekhar et al in 2010. Their study provided excellent yields of the corresponding 1,2‐diketones.…”

Section: Synthetic Strategies For Quinoxalinesmentioning

confidence: 94%

Quinoxaline‐Based Scaffolds Targeting Tyrosine Kinases and Their Potential Anticancer Activity

Newahie

Ismail

Ella

et al. 2016

Archiv der Pharmazie

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Quinoxaline derivatives, also called benzopyrazines, are an important class of heterocyclic compounds. Quinoxalines have drawn great attention due to their wide spectrum of biological activities. They are considered as an important basis for anticancer drugs due to their potential activity as protein kinase inhibitors. In this review, we focus on the chemistry of the quinoxaline derivatives, the strategies for their synthesis, their potential activities against various tyrosine kinases, and on the structure-activity relationship studies reported to date.

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Section: Synthetic Strategies For Quinoxalinesmentioning

confidence: 94%

Quinoxaline‐Based Scaffolds Targeting Tyrosine Kinases and Their Potential Anticancer Activity

Newahie

Ismail

Ella

et al. 2016

Archiv der Pharmazie

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“…Diphenylacetylenes (or tolans) are usually applied for larger systems which display interesting structural, electronic, nonlinear optical and luminescent properties . Oxidation of substituted tolans by Wacker reaction is one of the most useful methods for the synthesis of 1,2‐diketones . Although several methods have been reported for the oxidation of alkynes, these reactions still suffer from drawbacks such as harsh conditions, narrow substrate scope and low yield and/or chemoselectivity …”

Section: Introductionmentioning

confidence: 99%

Practical and theoretical aspects of Wacker oxidation of tolanophanes: Synthesis and characterization of novel diketonic cyclophanes

Darabi

Rastgar

Khatamifar

et al. 2017

Applied Organom Chemis

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Novel cyclophanes having 1,2-diketones 2a-c were synthesized by Wacker oxidation of the corresponding tolanophanes 1a-c having various alkyl chain lengths (n = 2-4). Among them, tolanophane 1a with the shortest alkyl chain length (n = 2) having more strained alkyne shows the lowest product selectivity even lower than that of acyclic analogues at various reaction temperatures. In contrast, the oxidation of tolanophane 1b (n = 3) is clean with the highest activity and selectivity of 2b. Theoretical calculations confirm the experimental data. Based on ab initio calculations, the critical step of the reaction pathway is the interaction of oxygen atoms of 1 (in the absence of H 2 O) with Pd ion of intermediate [PdCl 3 (1)] − to give [PdCl 2 (1)] which keeps Pd ion close to the alkyne bond. This step is not observed computationally for 1a because the positions of the oxygen atoms are outside of its central part. This is in good agreement with almost no activity of 1a at room temperature to prove its rigid structure preventing the O…Pd interaction. Nevertheless, the alkyne…Pd interaction of 1b is not detected by NMR measurements which may be due to its too slow interaction at room temperature (35% after 24 h); however, this confirms ab initio calculation data that the preferred coordinating site is oxygen in the reaction pathway. In contrast, cyclic voltammetry measurements distinguish a different behaviour for the palladium complexation of 1. In general, it is found that the stereochemistry of tolanophanes rather than distortion of alkyne bond plays the critical role in the oxidation. The products are new and their structures were characterized.

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“…Rhenium‐4 and palladium‐catalyzed5 processes that employ either hydrogen peroxide, dioxygen, sulfoxides, or pyridine N ‐oxide as the oxidant have been reported. These catalysts generally perform very well with diarylalkynes, but their procedures require high catalyst loadings (5–10 mol‐%) and/or high temperatures (60–140 °C) 6. An interesting Au/Ag catalytic system that uses diphenyl sulfoxide as the oxidant was recently reported as an efficient system for the synthesis of benzil derivatives and α‐oxo imides 7.…”

Section: Introductionmentioning

confidence: 99%

Ruthenium‐Catalyzed Synthesis of 1,2‐Diketones from Alkynes

et al. 2014

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Oxidation of alkynes using PdCl2/CuCl2 in PEG as a recyclable catalytic system: one-pot synthesis of quinoxalines

Cited by 71 publications

References 28 publications

Quinoxaline‐Based Scaffolds Targeting Tyrosine Kinases and Their Potential Anticancer Activity

Quinoxaline‐Based Scaffolds Targeting Tyrosine Kinases and Their Potential Anticancer Activity

Practical and theoretical aspects of Wacker oxidation of tolanophanes: Synthesis and characterization of novel diketonic cyclophanes

Ruthenium‐Catalyzed Synthesis of 1,2‐Diketones from Alkynes

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