Progress in Metathesis Chemistry, Beilstein J. Org. Chem. 2010, 6, 1089. Beilstein Journal of Organic Chemistry started a thematic series last year on olefin metathesis, including several review articles and research papers with Karol Grela as the guest editor. I enjoyed reading Benjamin Davis’ review on the allylic chalcogen effect in olefin metathesis. It’s been […]
Lowdown on Catalyst Loadings in Ru-catalyzed Metathesis Reactions
When reviewing the scientific literature related to ruthenium-catalyzed olefin metathesis, it is common place to observe the use of relatively high catalyst loadings. Typically, catalyst loadings employed are in the range of 1-5 mol% or greater depending on the specific application. An immediate question arises: Are these types of catalyst loadings required…or is it a […]
ROMP Toolbox: Controlling Metathesis Polymerizations
Leitgeb A.; Wappel J.; Slugovc C. The ROMP toolbox upgraded. Polymer 2010, 51, 2927-2946. Slugovc C. The Ring Opening Metathesis Polymerisation Toolbox. Macromol. Rapid Commun. 2004, 25, 1283-1297. Metathesis chemistry has been the subject of numerous books and review articles, but the vast majority of these sources focus on molecular synthesis or kinetic investigations, with […]
Finding the Right Metathesis Catalyst
White D.E.; Stewart I.C.; Seashore-Ludlow B.A.; Grubbs R.H.; Stoltz B.M. A General Enantioselective Route to the Chamigrene Natural Product Family. Tetrahedron 2010, 66, 4648-86. Finding the right metathesis catalyst for your reaction is easy – when the Grubbs group is next door… The Stolz group recently published the syntheses of several members of the chamigrene […]
Monitoring Non-Productive Metathesis in RCM Reactions
Stewart, I. C.; Keitz, B. K.; Kuhn, K. M.; Thomas, R. M.; Grubbs, R. H. J. Am. Chem. Soc. 2010, 132, 8534-8535. One challenge of mechanistic studies of reversible reactions is that it’s hard to be sure whether there are reversible steps going on that you’re not monitoring. In the case of ring closing metathesis […]
Books on Olefin Metathesis
Until very recently, there were basically two main books on olefin metathesis: Olefin Metathesis and Metathesis Polymerization (1997) edited by K. J. Ivin and J.C. Mol In retrospect, it could be titled: Metathesis Before the Ruthenium Era. Even though I have been working in the field for some time, I was amazed by the depth […]
Intermediates and Ring Closing Metathesis
Va der Eide, E.F.; Piers, W. E. Nature Chem. 2010, 2, 571-576. The ring closing metathesis (RCM) reaction has become a “standard” in olefin metathesis chemistry. However, there are a number of unobserved yet implied intermediates assumed to exist. As a consequence, little is known about the energetics of all the processes involved. Upon reading […]
Catalysts for Asymmetric Olefin Metathesis
When it comes to asymmetric olefin metathesis, molybdenum catalysts are generally better than their ruthenium homologues. However, chiral ruthenium metathesis catalysts have also been designed for asymmetric metathesis, with some success. Two main examples are the C2 symmetric catalyst 1 developed by Grubbs and the Hoveyda complex 2 featuring a bidentate ligand.1,2 Building upon those […]
Everything (or almost) about the 2nd Generation Grubbs Catalysts
Samojłowicz, C.; Bieniek, M.; Grela, K. Ruthenium-based olefin metathesis catalysts bearing N-heterocyclic carbene ligands, Chem. Rev. 2009, 109, 3708 – 3742. Vougioukalakis, G. C.; Grubbs, R. H. Ruthenium-based heterocyclic carbene-coordinated olefin metathesis catalysts, Chem. Rev. 2010, 110, 1746 – 1787. For metathesis, the 00’s was the decade of the second generation ruthenium catalysts. Besides the […]
Overcoming Substrate Bias with Metathesis Catalyst Selection
When justifying natural product synthesis, it’s often said that total synthesis provides a vehicle for the discovery of novel modes of chemical reactivity that otherwise wouldn’t be noticed. A nice example of this concept in action is out this week from researchers in Brian Stoltz’s group.1 During a total synthesis of the natural product curvularin, […]
Stereochemical Control in Metathesis by Hydrogen Bonding
Hoveyda, A. H.; Lombardi, P. J.; O’Brien, R. V.; Zhugralin, A. R. H-Bonding as a control element in stereoselective Ru-catalyzed olefin metathesis J. Am. Chem. Soc. 2009, 131, 8378-8379 Amir Hoveyda’s group recently demonstrated that H-bonding can significantly increase the rate and levels of stereochemical control in Ru-catalyzed olefin metathesis reactions. They developed facile diastereoselective […]