title: Regioselective rhodium-catalyzed intermolecular [2+2+2] cycloaddition of alkynes and isocyanates to form pyridones.
abstract: A highly regioselective rhodium-catalyzed intermolecular [2+2+2] cycloaddition of terminal alkynes with a variety of isocyanates to provide 2- and 4-pyridones has been developed. This reaction proceeds in good to excellent yields and overcomes the problem of dimerization and trimerization through the use of phosphoramidite ligands. A CO migration in the metallacycle is proposed to account for the formation of 4-pyridone.
authors.affiliation: Department of Chemistry, Colorado State Univeristy, Fort Collins, CO 80523, USA.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Oberg
authors.forename: Ernest E
authors.initials: EE
authors.lastname: Lee
authors.forename: Tomislav
authors.initials: T
authors.lastname: Rovis