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)3RuCl2(PCy3)], which was found to be an efficient promoter for atom transfer radical reactions under the adopted experimental conditions.
Highlights
During the course of our investigations on homobimetallic ruthenium–arene complexes, we found that the indenylidene compound [(p-cymene)Ru(μ-Cl)3RuCl(3-phenyl-1-indenylidene)(PCy3)] (1) was a very efficient promoter for the ringclosing metathesis (RCM) of diethyl 2,2-diallylmalonate [1]
We have demonstrated that homobimetallic ruthenium–indenylidene complex 1 is a suitable catalyst precursor for the tandem RCM/ATRC of polyhalogenated α,ω-dienes 4 and 8 into the corresponding bicyclic γ-lactam derivatives
The individual steps were carefully monitored by 1H and 31P NMR spectroscopies in order to understand the intimate details of the catalytic cycles
Summary
During the course of our investigations on homobimetallic ruthenium–arene complexes, we found that the indenylidene compound [(p-cymene)Ru(μ-Cl)3RuCl(3-phenyl-1-indenylidene)(PCy3)] (1) was a very efficient promoter for the ringclosing metathesis (RCM) of diethyl 2,2-diallylmalonate [1].Contrastingly, this catalyst precursor was almost inactive in the self-metathesis of styrene, as stilbene formation leveled off after a few minutes without going past the 10% threshold. We investigate the tandem catalysis of RCM/ATRC reactions with homobimetallic ruthenium–indenylidene complex 1 to generate active species in situ. The RCM of this functionalized α,ω-diene was carried out in toluene-d8 (0.2 M) at 30 °C in the presence of 5 mol % of catalyst precursor 1 and monitored by 1H NMR spectroscopy.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
