title: alpha-(Arylthio)imidoyl Radicals: [3 + 2] Radical Annulation of Aryl Isothiocyanates with 2-Cyano-Substituted Aryl Radicals.
abstract: A novel cascade radical reaction is described involving aryl isothiocyanates and 2-cyanoaryl radicals. The mechanism entails the formation of an alpha-(arylthio)imidoyl radical, a 5-exo-dig cyclization onto a cyano group, and a final 6-membered ring closure of an iminyl radical. The competitive 5-membered spiro-cyclization of the iminyl, leading to an isomeric product, was only observed in the case of a disubstituted aryl isothiocyanate. The whole process involves a rare example of [3 + 2] radical annulation and allows the one-pot synthesis of tetracondensed nitrogen heterocycles in good yields.
authors.affiliation: Dipartimento di Chimica Organica "A. Mangini", Università di Bologna, viale Risorgimento 4, I-40136 Bologna, Italy.
authors.forename: Rino
authors.initials: R
authors.lastname: Leardini
authors.forename: Daniele
authors.initials: D
authors.lastname: Nanni
authors.forename: Patrizia
authors.initials: P
authors.lastname: Pareschi
authors.forename: Antonio
authors.initials: A
authors.lastname: Tundo
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Zanardi