title: Advances in the Pauson-Khand reaction: development of reactive cobalt complexes.
abstract: Three conceptually new methods employing reactive cobalt carbonyl complexes have been developed for the Pauson-Khand reaction. The first method involves activation of alkyne-dicobalt hexacarbonyls with "hard" Lewis bases. Primary amines dramatically promote the stoichiometric Pauson-Khand reaction. The active cobalt complexes produced in the system exhibit high reducing ability. The second method involves activation of dicobalt octacarbonyl with less electron-donating "hard" Lewis bases such as 1,2-dimethoxyethane and water. These Lewis bases were successfully utilized as a promoter for the catalytic Pauson-Khand reaction. The third method employs methylidynetricobalt nonacarbonyl cluster, which exhibits high reactivity in the catalytic Pauson-Khand reaction in the absence of activator. This may be due to facile coordination of the substrate to the metal center through dissociative and associative mechanisms and/or cleavage of one of the cobalt-cobalt bonds.
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Japan. taku@ph.bunri-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Sugihara
authors.forename: M
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: M
authors.initials: M
authors.lastname: Nishizawa