Radical addition to aromatic aldoximes
Abstract
The e.s.r. spectra of the hydronitroxide radicals ArCHX-NHȮ, obtained by reaction of a number of aromatic aldoximes ArCHNOH (Ar = phenyl, 3- and 4-pyridyl, 2- and 3-thienyl, 2-furyl) with radicals X˙(X = MeS, BunS, Et3Si, Ph3Ge), have been detected. Assignment of the α- and β-proton splittings has been achieved by means of deuterium labelling. The analysis of the hyperfine splittings supports the hypothesis that the radicals ArCH(SR)-NHȮ adopt a single preferred conformation whereas the radicals ArCH(SiEt3)-NHȮ and ArCH(GePh3)-NHȮ undergo a rotational pathway through a variety of torsional conformers.