Retracted: tert‐ Butyl Hydroperoxide and Tetrabutylammonium Iodide‐ Promoted Free Radical Cyclization of α‐Azido‐ N ‐arylamides

Abstract

The oxidizing system of tert ‐butyl hydroperoxide (TBHP) and tetrabutylammonium iodide (TBAI) is capable of engendering α‐(aminocarbonyl)iminyl radicals from α‐azido‐ N ‐phenylacetamides. These iminyl radicals preferably undergo intramolecular attack on the benzene ring to give azaspirocyclohexadienyl radicals, which are readily captured by O 2 under an oxygen atmosphere to yield azaspirocyclohexadienones. In the absence of oxygen, the reaction will afford quinoxalin‐2‐one products. The generation of α‐(aminocarbonyl)iminyl radicals is proposed to involve an initial deprotonation and denitrogenation, and subsequent oxidation of thus formed imine intermediates by tert ‐butoxy radical and/or tert ‐butyl peroxyl radical. magnified image