Co-catalyst dependent cycloisomerization or ring closing metathesis of α,ω-dienes catalyzed by arene ruthenium complex with side-arm alcohol

Homobimetallic Ruthenium–N‐Heterocyclic Carbene Complexes: Synthesis, Characterization, and Catalytic Applications

“…Yet, conversions were slightly lower and cycloisomerization took precedence over RCM, in line with the reduced metathetical activity of 3b compared to 3a. Reports from the groups of Kurosawa [31] and Dixneuf [32] had already established that selected monometallic ruthenium-arene complexes displayed such a dual activity. A mechanism involving oxidative coupling of the diene to a ruthenium(II) center followed by b-elimination to generate a hydrido-ruthenium(IV) intermediate and reductive elimination was proposed to account for the cycloisomerization process (Scheme 3).…”

“…[31,32] The alkyne co-catalyst probably reacts with coordinatively unsaturated ruthenium centers to form vinylidene species. Although less active than their alkylidene counterparts, complexes featuring an Ru=C=CHR moiety are wellknown initiators for various types of olefin metathesis, including ROMP and RCM (Scheme 4).…”

Preparation, Reactivity and Peptide Labelling Properties of (η6‐Arene)ruthenium(II) Complexes with Pendant Carboxylate Groups

“…[1,2] Examples of chelating side-chains have included amines, [1] alcohols, [1Ϫ3] thioethers, [4] and phosphanes. [1,5Ϫ9] Chloro-bridged complexes of the type [{(η 6 -arene)Ru(µ-Cl)Cl} 2 ] with N-terminal protected derivatives of phenylglycine ethyl ester as the functionalised arene ligand have also been reported recently.…”

“…Quantitative formation of 8 can also be achieved in aqueous solution in the presence of a 3:1 excess of the {η 6 -C 6 H 5 (CH 2 ) 3 COOH}Ru II fragment. This can also be employed for the N-terminal labelling of amino acids and peptides in its sandwich complex [(η 6 -C 6 Me 6 )Ru{η 6 -C 6 H 5 (CH 2 ) 3 -COOH}](OTf) 2 (10). Coupling reactions by the carbodiimide method with EDC afford water-stable complexes of the type [(η 6 -C 6 Me 6 )Ru{η 6 -C 6 H 5 (CH 2 ) 3 C(O)R}](OTf) 2 [R = trpOMe (11), pheOMe (12), glyglyOEt (13) nylalanine residues but also for the more general N-terminal labelling of peptides.…”

Rhodium catalyzed tandem Diels-Alder/hydrolysis reactions of 2-boron-substituted 1,3-dienes

“…Since that time, we have reported a number of synthetic routes to these and other related types of cobalt dienyl complexes as well as their subsequent cycloaddition and demetallation chemistry, [3][4][5] and other groups have now made use of the cycloadducts thus prepared [6] as well as the methodology. [7] We initially tried to develop a cobalt catalyzed Diels-Alder sequence rather than the stoichiometric cobalt chemistry we originally described.…”