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Ring-closing metathesis has also been used to cyclize rings containing an alkyne to produce a new terminal alkene, or even undergo a second cyclization to form bicycles. This type of reaction is more formally known as enyne ring-closing metathesis. [7] [45]
In one study published by Grubbs and Hong in 2006, a water-soluble Grubbs catalyst was prepared by attaching a polyethylene glycol chain to the imidazolidine group. [20] This catalyst is used in the ring-closing metathesis reaction in water of a diene carrying an ammonium salt group making it water-soluble as well.
Ring-opening metathesis usually involves a strained alkene (often a norbornene) and the release of ring strain drives the reaction. Ring-closing metathesis, conversely, usually involves the formation of a five- or six-membered ring, which is enthalpically favorable; although these reactions tend to also evolve ethylene, as previously discussed.
Grubbs was instrumental in developing a family of ruthenium catalysts, including Grubbs catalyst for olefin metathesis. [36] He studied olefin transformations for ring-closing metathesis (RCM), [37] cross-metathesis reaction (CMR), [38] and ring-opening metathesis polymerization (ROMP) with cyclic olefins such as norbornene. [39]
An enyne metathesis is an organic reaction taking place between an alkyne and an alkene with a metal carbene catalyst forming a butadiene. This reaction is a variation of olefin metathesis. [1] The general scheme is given by scheme 1: When the reaction is intramolecular (in an enyne) it is called ring-closing enyne metathesis or RCEYM (scheme 2):
In polymer chemistry, ring-opening metathesis polymerization (ROMP) is a type of chain-growth polymerization involving olefin metathesis. [1] The reaction is driven by relieving ring strain in cyclic olefins. [2] A variety of heterogeneous and homogeneous catalysts have been developed for different polymers and mechanisms. [3] Heterogeneous ...
Alkyne metathesis is an organic reaction that entails the redistribution of alkyne chemical bonds. The reaction requires metal catalysts. The reaction requires metal catalysts. Mechanistic studies show that the conversion proceeds via the intermediacy of metal alkylidyne complexes .
The Zhan catalysts were inspired by previous work in the olefin metathesis field. Robert H. Grubbs first reported the first and second generation of Ru catalysts in 1992, with good metathesis activity. However, the catalysts containing the tricyclohexylphospine ligand were unstable to air and water, and the catalytic activity is not good enough ...