metathesis of proteins under aqueous conditions, which makes a powerful reaction in organic and polymer chemistry potentially available for the elaboration of biopolymers. The work by Davis and colleagues raises two follow-up questions regarding the versatility of the metathesis approach and its implementation under physiological conditions. The present study tests metathesis of proteins on a r...

Tandem dehydrogenation-olefin-metathesis catalyst systems, comprising a pincer-ligated iridium-based alkane dehydrogenation catalyst and a molybdenum-based olefin-metathesis catalyst, are reported to effect the metathesis-cyclooligomerization of cyclooctane and cyclodecane to give cycloalkanes with various carbon numbers, predominantly multiples of the substrate carbon number, and polymers.

Copper(I) halides are employed as ‘phosphine sponges’ to sequester phosphor-ylides when using phosphine-based Grubb’s metathesis catalysis in polar protic solvents and under heat. These cuprous halides are hypothesized to significantly slow the formation of the ruthenium hydride olefin isomerization catalyst. We demonstrate their use in both cross metathesis and ring-closing metathesis.

Dimethyl (β-substituted) vinylphosphonates do not readily undergo cross metathesis reactions with Grubbs catalyst and terminal alkenes. However, the corresponding mono- or diallyl vinylphosphonate esters undergo facile cross metathesis reactions. The improved reactivity is attributed to a relay step in the cross metathesis reaction mechanism.

A homogeneous mixture of Grubbs' catalyst in paraffin wax was shown to catalyze three important types of metathesis reactions: ring-closing metathesis, alkene dimerization, and alkene cross-metathesis (e.g., 11 --> 13). This catalyst preparation demonstrated no loss in catalytic activity after 22 months of storage open to the air.

Tuning the electronic and steric environment of olefin metathesis catalysts with specialized ligands can adapt them to broader applications, including metathesis in aqueous solvents. Bidentate salicylaldimine ligands are known to stabilize ruthenium alkylidene complexes, as well as allow ring-closing metathesis in protic media. Here, we report the synthesis and characterization of exceptionally...

Several new C-H-activated ruthenium catalysts for Z-selective olefin metathesis have been synthesized. Both the carboxylate ligand and the aryl group of the N-heterocyclic carbene have been altered and the resulting catalysts evaluated using a range of metathesis reactions. Substitution of bidentate with monodentate X-type ligands led to a severe attenuation of metathesis activity and selectivi...

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...

Alkenes containing N-heteroaromatics are known to be poor partners in cross-metathesis reactions, probably due to catalyst deactivation caused by the presence of a nitrogen atom. However, some examples of ring-closing and cross-metathesis involving alkenes that incorporate N-heteroaromatics can be found in the literature. In addition, recent mechanistic studies have focused on the rationalizati...

Judeo-Spanish denotes those varieties of Spanish preserved by the Sephardic Jews who were expelled from Spain in 1492 and have emigrated throughout Europe, North Africa, the Middle East, and the United States. This paper examines three types of consonant metathesis in Judeo-Spanish: daldo < dadlo ‘give it’, terné ‘I will have’ < tener ‘to have’, and tadre < tarde ‘late, afternoon’. The first tw...