A design-of-experiments approach for the optimization and understanding of the cross-metathesis reaction of methyl ricinoleate with methyl acrylate

p-Cymene as Solvent for Olefin Metathesis: Matching Efficiency and Sustainability

The underexploited biorenewable p-cymene is employed as a solvent for the metathesis of various substrates. p-Cymene is a nontoxic compound that can be obtained in large amounts as a side product of the cellulose and citrus industry. For the cross-metathesis of estragole with methyl acrylate, this solvent prevents the consecutive double-bond isomerization of the product and affords the best yield of all solvents tested. Undesired consecutive isomerization is a major challenge for many substrates in olefin metathesis, including pharmaceutical precursors, and the use of p-cymene as a solvent may be a way to prevent it. This solvent results in a better metathesis performance than toluene for the three substrates tested in this work, matching its performance for two other substrates.

Augmentation of productivity in olefin cross-metathesis: maleic acid does the trick!

Why use the protected esters when the free acids result in better catalytic performances?

Tandem catalysis versus one-pot catalysis: ensuring process orthogonality in the transformation of essential-oil phenylpropenoids into high-value products via olefin isomerization–metathesis

One-pot and tandem catalysis methodologies are explored in developing efficient isomerization–metathesis routes to high-value cinnamates and ferulates from essential-oil allylbenzenes.

Acrylate metathesis via the second-generation Grubbs catalyst: unexpected pathways enabled by a PCy3-generated enolate

The diverse applications of acrylate metathesis range from synthesis of high-value α,β-unsaturated esters to depolymerization of unsaturated polymers. Examined here are unexpected side reactions promoted by the important Grubbs catalyst GII. Evidence is presented for attack of PCy3 on the acrylate olefin to generate a reactive carbanion, which participates in multiple pathways, including further Michael addition, proton abstraction, and catalyst deactivation. Related chemistry may be anticipated whenever labile metal-phosphine complexes are used to catalyze reactions of substrates bearing an electron-deficient olefin.

Improving sustainability in ene-yne cross-metathesis for transformation of unsaturated fatty esters

Ruthenium-catalyzed ene-yne cross-metathesis is performed with stoichiometric proportions of terminal olefins and alkynes. This is made possible by the continuous addition of the alkyne to the reaction mixture. The protocol allows the ene-yne cross-metathesis reaction to be carried out with long-chain terminal olefins and in a one-pot fashion with internal olefins after shortening by ethenolysis. The efficient conversion of renewable unsaturated fatty esters from bioresources into valuable conjugated 1,3-dienes of interest for further transformations is performed using this technique under mild conditions in dimethyl carbonate; an ecofriendly solvent.