title: Increasing the structural span of alkyne metathesis.
abstract: A new generation of alkyne metathesis catalysts, which are distinguished by high activity and an exquisite functional group tolerance, allows the scope of this transformation to be extended beyond its traditional range. They accept substrates that were previously found problematic or unreactive, such as propargyl alcohol derivatives, electron-deficient and electron-rich acetylenes of various types, and even terminal alkynes. Moreover, post-metathetic transformations other than semi-reduction increase the structural portfolio, as witnessed by the synthesis of a annulated phenol derivative via ring-closing alkyne metathesis (RCAM) followed by a transannular gold-catalyzed Conia-ene reaction. Further examples encompass a post-metathetic transannular ketone-alkyne cyclization with formation of a trisubstituted furan, a ruthenium-catalyzed redox isomerization, and a Meyer-Schuster rearrangement/oxa-Michael cascade. These reaction modes fueled model studies toward salicylate macrolides, furanocembranolides, and the cytotoxic macrolides acutiphycin and enigmazole A; moreover, they served as the key design elements of concise total syntheses of dehydrocurvularin (27) and the antibiotic agent A26771B (36).
authors.affiliation: Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr (Germany), Fax: (+49) 208 306 2994.
authors.forename: Peter
authors.initials: P
authors.lastname: Persich
authors.forename: Josep
authors.initials: J
authors.lastname: Llaveria
authors.forename: Rudy
authors.initials: R
authors.lastname: Lhermet
authors.forename: Teresa
authors.initials: T
authors.lastname: de Haro
authors.forename: Robert
authors.initials: R
authors.lastname: Stade
authors.forename: Azusa
authors.initials: A
authors.lastname: Kondoh
authors.forename: Alois
authors.initials: A
authors.lastname: Fürstner
keywords: alkyne metathesis; gold; molybdenum; natural products; total synthesis; transannular reactions