title: Synthesis of seven-membered ring diazepin-2-ones via palladium-catalyzed highly regioselective cyclization of 2-vinylpyrrolidines with aryl isocyanates.
abstract: The first palladium-catalyzed ring-expansion reaction of 2-vinylpyrrolidines with aryl isocyanates to form seven-membered ring heterocycles is described. This regioselective reaction requires 5 mol % of Pd(2)(dba)(3).CHCl(3) and 10 mol % of dppp at 40-60 degrees C in THF and results in the formation of 1,3-diazepin-2-ones in good isolated yields. When Pd(OAc)(2) and PPh(3) were utilized in the reaction, an intramolecular hydrogen migration occurs resulting in the formation of conjugated diene derivatives of urea.
authors.affiliation: Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: Hai-Bing
authors.initials: HB
authors.lastname: Zhou
authors.forename: Howard
authors.initials: H
authors.lastname: Alper