An unusual thermal oxidation of triaryloxazoles. Issue 23 (3rd June 2015)

• Record Type: Journal Article
• Authors: Pickett, James E.
• Is Part Of: Tetrahedron letters. Volume 56:Issue 23(2015)
• Page Start: 3023
• Page End: 3026
• Publication Date: 2015-06-03
• Subjects: Spin forbidden -- Triplet oxygen -- Oxazole -- Oxidation; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2014.10.072
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Abstract: Triaryloxazoles undergo slow but smooth thermal oxidation at 135–175 °C to produce nitrile and anhydride products apparently arising from endoperoxides formed from the addition of oxygen to the heterocyclic ring. The Hammett ρ value of ca. −0.7 and activation energy of ca. 87 kJ/mol (21 kcal/mol) seemed to rule out an electron-transfer mechanism. A mechanism involving a peroxidic biradical and a triplet to singlet spin flip is suggested.