The ground-breaking advances in catalytic olefin metathesis by Grubbs and others have revolutionized many aspects of organic synthesis, ensuring a high general level of interest in the key metal alkylidene catalysts. The mechanism of ruthenium-mediated olefin metathesis catalysed by first (1a) and second generation (1b) Grubbs complexes has been extensively studied both by experiment and by com...

A highly selective method for the synthesis of asymmetrically substituted carbocycles and heterocycles from unactivated aldehyde-olefin precursors has been achieved via enantioselective SOMO-catalysis. Addition of a catalytically generated enamine radical cation across a pendent olefin serves to establish a general asymmetric strategy toward the production of a wide range of formyl-substituted ...

Oxidative annulations for the synthesis of carbocycles were developed using a catalytic palladium(II) system. Indoles with pendant olefin tethers were oxidatively cyclized to form annulated products. Electron-rich aromatic systems were also investigated, culminating in the synthesis of benzofurans and dihydrobenzofurans by a similar protocol. These reactions were demonstrated to proceed by an i...

He(I) and He(II) photoelectron spectra are reported for (/^-CsHs^MLX (M = Nb, Ta; L = H, CO; X — propene, 1-butene, propyl) and some methylcyclopentadienyl derivatives. Also the spectra of some yr-allyl and dihalide complexes are reported. Unambiguous assignments could be made of the metal d ai orbital, the Cp orbitals, the olefin n ionization and the M-hydride and 7t-allyl orbitals. Very regul...

Heteroatom-functionalized polyolefins are of fundamental interest and practical importance. This has spurred investigations of the copolymerization of polar and nonpolar olefins. We report the first syndiospecific polymerization of a series of heteroatom-containing α-olefins and their copolymerization with ethylene catalyzed by half-sandwich rare-earth complexes. We have found that the interact...

For a reaction to be generally useful for protein modification, it must be site-selective and efficient under conditions compatible with proteins: aqueous media, low to ambient temperature, and at or near neutral pH. To engineer a reaction that satisfies these conditions is not a simple task. Olefin metathesis is one of most useful reactions for carbon-carbon bond formation, but does it fit the...

Light activation is a most desirable property for catalysis control. Among the many catalytic processes that may be activated by light, olefin metathesis stands out as both academically motivating and practically useful. Starting from early tungsten heterogeneous photoinitiated metathesis, up to modern ruthenium methods based on complex photoisomerisation or indirect photoactivation, this surve...

A highly selective cascade reaction that allows the direct transformation of dienallenes to spirocyclobutenes (spiro[3.4]octenes) as single isomers has been developed. The reaction involves formation of overall four C-C bonds and proceeds via a palladium-catalyzed oxidative transformation with insertion of olefin, olefin, and carbon monoxide. Under slightly different reaction conditions an addi...

The interplay between olefin metathesis and dendrimers and other nano systems is addressed in this mini review mostly based on the authors' own contributions over the last decade. Two subjects are presented and discussed: (i) The catalysis of olefin metathesis by dendritic nano-catalysts via either covalent attachment (ROMP) or, more usefully, dendrimer encapsulation - ring closing metathesis (...

The asymmetric synthesis of [7]helicene was accomplished in good ee (80%) by kinetic resolution by means of asymmetric olefin metathesis. Three key factors contributed to the success of the kinetic resolution: the use of new Ru-based olefin metathesis catalysts bearing C1-symmetric N-heterocyclic carbene ligands, simple olefins as additives to control the nature of the propagating alkylidene an...