Unusual Reactivity of 4-Vinyl Isoxazoles in the Copper-Mediated Synthesis of Pyridines, Employing DMSO as a One-Carbon Surrogate
作者:Pravin Kumar、Manmohan Kapur
DOI:10.1021/acs.orglett.0c01935
日期:2020.8.7
An efficient protocol for the synthesis of nicotinate derivatives and tetrasubstituted pyridines through a copper-mediated cleavage of isoxazoles has been developed. The highlight of the work is the observation of an unusualreactivity of 4-vinyl isoxazoles under the reaction conditions. DMSO serves as a one-carbon surrogate generating an active methylene group during the reaction to form two C–C bonds
Cycloisomerization of acetylenic oximes and hydrazones under gold catalysis: Synthesis and cytotoxic evaluation of isoxazoles and pyrazoles
作者:J C JEYAVEERAN、CHANDRASEKAR PRAVEEN、Y ARUN、A A M PRINCE、P T PERUMAL
DOI:10.1007/s12039-015-0993-9
日期:2016.1
The synthesis of substituted isoxazoles and pyrazoles through a general cycloisomerization methodology has been reported. The capability of gold(III) chloride to promote cycloisomerization of both α, β-acetylenic oximes and α, β-acetylenic hydrazones is the centrepiece of the strategy. A range of acetylenic precursors were investigated to afford 28 examples of the products with good to excellent chemical yields. Selected compounds were screened for their cytotoxic potential towards COLO320 cancer cell lines. The IC50 values of the tested compounds were in the micromolar range, with the best compound, 5-(6-Methoxy-naphthalen-2-yl)-3-phenyl-isoxazole (3h) displaying an IC50 of 38.9 μM. For this compound, the crystal structure in complex with Aurora-A kinase was obtained which revealed details of its binding mode within the active site with a free energy of binding -9.54 kcal/mol.
A Copper‐Catalyzed Synthesis of Pyrroles through Photochemically Generated Acylazirines
作者:Jan Paternoga、Till Opatz
DOI:10.1002/ejoc.201901176
日期:2019.11.14
A protocol for the synthesis of highly substituted 2,4‐diacypryrroles via a copper‐catalyzed ring strain releasing dimerization reaction was developed. The pyrroles are synthesized combining UV–photochemistry and metal‐catalyzed follow up reaction in an one‐pot system. To match the rates of the thermal and the photoinduced step, an internal temperature control was established.
Synthesis of Isoxazolines and Isoxazoles via Metal-Free Desulfitative Cyclization
作者:Qiu Sun、Ling He、Jiaxin Cheng、Ze Yang、Yuansheng Li、Yulan Xi
DOI:10.1055/s-0037-1609480
日期:2018.6
bonds/construction of C–O bonds/elimination of SO2/C–N bond formation is achieved in sequence in the reaction system. A novel, one-pot reaction for the synthesis of isoxazolines and isoxazoles is developed via a cascade process under metal-free conditions. The approach involves the formation of intramolecular C–N and C–O bonds and intermolecular C–C bonds from aromatic alkenes or alkynes and N-hydroxysulfonamides