An environmentally benign synthesis of isoxazolines and isoxazoles mediated by potassium chloride in water
An effective and environmentally benign procedure for the synthesis of isoxazolines and isoxazoles has been developed by a cycloaddition of nitrile oxides with alkenes or alkynes in water. In this approach, potassium chloride is first oxidized into chlorine in water by the environmentally friendly oxidant Oxone, then aldoximes are oxidized into nitrile oxides by the in situ generated hypochlorous acid, finally a 1,3-dipolar cycloaddition between nitrile oxides and alkenes or alkynes occurs to provide the corresponding isoxazolines and isoxazoles in good yields.
Han, Liuquan,Zhang, Bijun,Zhu, Min,Yan, Jie
supporting information
p. 2308 - 2311
(2014/04/17)
KF/Al2O3: Solid-supported reagent used in 1,3-dipolar cycloaddition reaction of nitrile oxide
The stereoselective synthesis of 2-isoxazolidine through 1,3-dipolar cycloaddition reaction of nitrile oxide, which is in situ generation from aldoxime in the presence of N-bromosuccinamide and solid-supported reagent KF/Al2O3 at room temperature, is reported. KF/Al2O3 is sufficiently basic such that it can replace organic bases such as Et 3N used in typical procedures and it catalyses the reaction to enhance the rate of the reaction.
Boruah, Monalisa,Konwar, Dilip
p. 3261 - 3268
(2012/09/11)
Use of Nitrile Oxides in Synthesis. A Novel Synthesis of Chalcones, Flavanones, Flavones and Isoflavones
Novel methodology is developed for a three-step synthesis of chalcones, flavanones, flavones and isoflavones. 1.Salicylaldoxime is chlorinated to the corresponding hydroxamoyl chloride in the presence of pyridine, and cycloadded to styrene and phenylacetylene. 2.The isoxazole derivatives formed are reductively cleaved over Raney-Ni to β-hydroxyketones or 1,3 diketones. 3.Acid-catalyzed cyclization gives the flavonoids.Use of ω-methoxy- or ω-dialkylamino-substituted styrenes (enamines) leads regioselectively to 4-aryl-substituted isoxazoles and derived isoflavones.
Thomsen, Ib,Torssell, Kurt B. G.
p. 303 - 308
(2007/10/02)
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