85 research outputs found

    Catalytic Transformations of Alkynes via Ruthenium Vinylidene and Allenylidene Intermediates

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    NOTICE: This is the peer reviewed version of the following book chapter: Varela J. A., González-Rodríguez C., Saá C. (2014). Catalytic Transformations of Alkynes via Ruthenium Vinylidene and Allenylidene Intermediates. In: Dixneuf P., Bruneau C. (eds) Ruthenium in Catalysis. Topics in Organometallic Chemistry, vol 48, pp. 237-287. Springer, Cham. [doi: 10.1007/3418_2014_81]. This article may be used for non-commercial purposes in accordance with Springer Verlag Terms and Conditions for self-archiving.Vinylidenes are high-energy tautomers of terminal alkynes and they can be stabilized by coordination with transition metals. The resulting metal-vinylidene species have interesting chemical properties that make their reactivity different to that of the free and metal π-coordinated alkynes: the carbon α to the metal is electrophilic whereas the β carbon is nucleophilic. Ruthenium is one of the most commonly used transition metals to stabilize vinylidenes and the resulting species can undergo a range of useful transformations. The most remarkable transformations are the regioselective anti-Markovnikov addition of different nucleophiles to catalytic ruthenium vinylidenes and the participation of the π system of catalytic ruthenium vinylidenes in pericyclic reactions. Ruthenium vinylidenes have also been employed as precatalysts in ring closing metathesis (RCM) or ring opening metathesis polymerization (ROMP). Allenylidenes could be considered as divalent radicals derived from allenes. In a similar way to vinylidenes, allenylidenes can be stabilized by coordination with transition metals and again ruthenium is one of the most widely used metals. Metalallenylidene complexes can be easily obtained from terminal propargylic alcohols by dehydration of the initially formed metal-hydroxyvinylidenes, in which the reactivity of these metal complexes is based on the electrophilic nature of Cα and Cγ, while Cβ is nucleophilic. Catalytic processes based on nucleophilic additions and pericyclic reactions involving the π system of ruthenium allenylidenes afford interesting new structures with high selectivity and atom economy

    Editorial of special issue ruthenium complex: The expanding chemistry of the ruthenium complexe

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    Recent trends in Ru complex chemistry are surveyed with emphasis on the development of anticancer drugs and applications in catalysis, polymers, materials science and nanotechnology

    Recent advances in metathesis-derived polymers containing transition metals in the side chain

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    This account critically surveys the field of side-chain transition metal-containing polymers as prepared by controlled living ring-opening metathesis polymerization (ROMP) of the respective metal-incorporating monomers. Ferrocene- and other metallocene-modified polymers, macromolecules including metal-carbonyl complexes, polymers tethering early or late transition metalcomplexes, etc. are herein discussed. Recent advances in the design and syntheses reported mainly during the last three years arehighlighted, with special emphasis on new trends for superior applications of these hybrid materials

    ROMP synthesis of iron-containing organometallic polymers

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    The paper overviews iron-containing polymers prepared by controlled “living” ring-opening metathesis polymerization (ROMP). Developments in the design and synthesis of this class of organometallic polymers are highlighted, pinpointing methodologies and newest trends in advanced applications of hybrid materials based on polymers functionalized with iron motifs

    Olefin metathesis as key step in the synthesis of bioactive compounds: Challenges in the total synthesis of irioteolides

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    Iriomoteolides are novel macrolides possessing either a unique 15-membered or a 20-membered macrocycle, and displaying exceedingly potent cytotoxicity with IC50 values of up to 2 ng/mL. Thus far, over a period of about four years, ten research groups worldwide have published their synthetic efforts resulting in four total syntheses of iriomoteolides and a few diastereomers thereof, and a number of fragment and macrocyclic core syntheses. Interestingly, three total syntheses involved ring-closing metathesis as the key step for the construction of the macrocycle, whereas the synthesis of three fragments was accomplished using a cross-metathesis reaction. Herein we highlight assets and limitations of the olefin metathesis reaction in the synthesis of the title compounds
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