Regio, stereo and chemoselectivity of 2nd generation Grubbs ruthenium-catalyzed olefin metathesis

Abstract

The examination of cross metathesis reactions leading to the desired product has been conducted to uncover computationally the origin of the chemo-, regio-and stereoselectivity. The comparison between the relative stabilities of all involved intermediates and products, together with the transition states, links to the probability for the respective pathway. Particularly, the respective transition states for each reaction tune the regio-and stereoselectivity because they lead to define the energy barriers needed to be overcome to form the new olefin as final product. The broad range of studied reactions with the 2 nd generation Grubbs catalysts allows concluding in detail the points to pay attention and thus helps to understand the chemo-, regio-and stereoselectivity in new olefin metathesis reactions. Here, a web-server joins all these mechanistic insights which is intented to support future predictive olefin metathesis catalysis.

Side-Chain Spacing Control of Derivatives of Poly(2-methoxyethyl acrylate): Impact on Hydration States and Antithrombogenicity

“…Although 13 C NMR measurement we applied was not quantitative, the signal intensity ratio revealed that P5 had a trans -olefin ( E -olefin) rich structure. In general, Ruthenium catalysts with N -heterocyclic carbene ligand (e.g., G2) show E -favorable metathesis . P7 and P8 also showed a trans -olefin ( E -olefin) rich structure.…”

“…In general, Ruthenium catalysts with N-heterocyclic carbene ligand (e.g., G2) show Efavorable metathesis. 28 P7 and P8 also showed a trans-olefin (E-olefin) rich structure. Contrary to this, P4 had a cis-rich structure, consistent with the report on the Z-favorable ROMP of 1-substituted cyclobutenes.…”

Role of Substrate Substituents in Alkene Metathesis Mediated by a Ru Alkylidene Catalyst

“…Finally, the newly formed Ru alkylidenes E resulting from the liberation of styrene preserve to a great extent the conformation of ligands as in TS­(D → E) . In the Ru alkylidene, E I a β-agostic interaction is found, similar to those recently found by Cavallo and co-workers …”

“…The continuous improvement of catalyst activity of the Ru family by modifying the complex architecture has resulted from detailed mechanistic studies that have shed light into the rate constants and activation energies and entropies. − As a complementary tool to experimental data on activity and reaction mechanisms, computational chemistry has played an essential role in determining the nature of active species and the most important intermediates (like metallacyclobutanes, for instance), in the calculation of reaction energies and activation energies and in the discrimination of the most feasible reaction pathways when competitive mechanisms are possible. − Regarding the latter, computational chemistry has been useful to discriminate among several activation mechanisms of Ru catalysts, ,− the selectivity during catalytic cycles, ,− the decomposition pathways, − or the recovery of chelating Ru benzylidenes . Most of the computational contributions on the olefin metathesis reaction with Ru alkylidenes involve the study of ligand effects in the catalysts and how the modifications in the complex architecture help to obtain more favorable reaction pathways and/or a particular product.…”

MOF Encapsulation of Ru Olefin Metathesis Catalysts to Block Catalyst Decomposition

“…Although it may seem like an easy redistribution of C-C double bonds [8,9], a thorough understanding of its mechanism, as well as any unwanted parallel processes that could decrease its efficiency are necessary [10][11][12][13]. If that were not enough, apart from the activity, then an additional effort is needed to control the chemo-, regio-and stereoselectivity of the metathesis [14][15][16].…”