Reactions of aldonitrones (3-imidazoline-3-oxides) with isothiocyanates

Cycloaddition of aldonitrones (derivatives of 3-imidazoline-3-oxide) to isothiocyanates depends on the N(1) substituent. Electron donating substituents facilitate cycloaddition to the C=N bond, whereas electron acceptors activate the C=S bond. Hydrolysis of adducts on the C=N bond followed by oxidation gives nitroxide radicals which are pH-sensitive spin probes.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2642–2647, November, 1991.