title: Tandem catalysis of ring-closing metathesis/atom transfer radical reactions with homobimetallic ruthenium-arene complexes.
abstract: The tandem catalysis of ring-closing metathesis/atom transfer radical reactions was investigated with the homobimetallic ruthenium-indenylidene complex [(p-cymene)Ru(μ-Cl)₃RuCl(3-phenyl-1-indenylidene)(PCy₃)] (1) to generate active species in situ. The two catalytic processes were first carried out independently in a case study before the whole sequence was optimized and applied to the synthesis of several polyhalogenated bicyclic γ-lactams and lactones from α,ω-diene substrates bearing trihaloacetamide or trichloroacetate functionalities. The individual steps were carefully monitored by ¹H and ³¹P NMR spectroscopies in order to understand the intimate details of the catalytic cycles. Polyhalogenated substrates and the ethylene released upon metathesis induced the clean transformation of catalyst precursor 1 into the Ru(II)-Ru(III) mixed-valence compound [(p-cymene)Ru(μ-Cl)₃RuCl(2)(PCy₃)], which was found to be an efficient promoter for atom transfer radical reactions under the adopted experimental conditions.
authors.affiliation: Laboratory of Macromolecular Chemistry and Organic Catalysis, Institut de Chimie (B6a), Université de Liège, Sart-Tilman par 4000 Liège, Belgium.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Borguet
authors.forename: Xavier
authors.initials: X
authors.lastname: Sauvage
authors.forename: Guillermo
authors.initials: G
authors.lastname: Zaragoza
authors.forename: Albert
authors.initials: A
authors.lastname: Demonceau
authors.forename: Lionel
authors.initials: L
authors.lastname: Delaude