Synthesis of 3-Acyl-isoxazoles and Δ<sup>2</sup>-Isoxazolines from Methyl Ketones, Alkynes or Alkenes, and <i>tert</i>-Butyl Nitrite via a Csp<sup>3</sup>–H Radical Functionalization/Cycloaddition Cascade
A novel metal-free tandem Csp3–H bond functionalization of ketones and 1,3-dipolar cycloaddition has been developed. An efficient approach to a variety of oxazole and isoxazoline derivatives is demonstrated using the 1,3-dipolar cycloaddition of alkynes and alkenes to nitrile oxides generated by reactions of methylketones with tert-butyl nitrite. This new protocol provides access to a variety of isoxazolines
A simple and direct method for the iron(III) nitrate-mediated synthesis of isoxazoles from alkynes has been developed; both self-coupling and cross-coupling products could be successfully prepared from alkynes. Meanwhile, for the cross-coupling and cyclizing of two different alkynes examined, the iron-mediated system shows a good chemoselectivity for the synthesis of corresponding isoxazoles. In our
Catalyst-Free Formation of Nitrile Oxides and Their Further Transformations to Diverse Heterocycles
作者:Luca De Angelis、Alexandra M. Crawford、Yong-Liang Su、Daniel Wherritt、Hadi Arman、Michael P. Doyle
DOI:10.1021/acs.orglett.0c04130
日期:2021.2.5
transfer from tert-butyl nitriteundermildconditions and without the use of a catalyst or an additive is reported. This transformation is broadly applicable to the synthesis of furoxans by dimerization and isoxazoles and isoxazolines by cycloaddition. This methodology is also applied for the millimole-scale synthesis of two biologically active compounds. The formation of the nitrile oxide from a diazoacetamide
Formation of isoxazole derivatives via nitrile oxide using ammonium cerium nitrate (CAN): a novel one-pot synthesis of 3-acetyl- and 3-benzoylisoxazole derivatives
作者:Ken-ichi Itoh、C.Akira Horiuchi
DOI:10.1016/j.tet.2003.11.088
日期:2004.2
4-diacetyl-1,2,5-oxadiazole 2-oxide) as the dimer of nitrile oxide. Moreover, it was found that yields of isoxazole derivatives were improved using ammonium cerium(III) nitrate tetrahydrate ((NH4)2Ce(NO3)5·4H2O, CAN(III))-formic acid. The reaction mechanisms based on nitration and formation of nitrile oxide mediated by CAN(IV) or CAN(III) from acetone or acetophenone are also proposed.
by the reaction of alkenes or alkynes with ketones (acetone or acetophenone), as both a reagent and the solvent, by three methods: iron(lll) nitrate under reflux, iron(III) salt-nitrogen dioxide (NO;) at room temperature, and iron(III) nitrate under microwave irradiation (MW).