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 […]

Ring Closing Metathesis Reaction Planning

Ring closing metathesis (RCM) has evolved into one of those coveted “predictable” reactions in organic synthesis. Sure, there are things that can go wrong, but for forming unstrained rings, it’s a great way to go. Substrate selection As with any time using a Grubbs catalyst system, you want to avoid certain functional groups. Coordinating groups […]

Ruthenium Removal After Metathesis Reactions

Knight, D. W.; Morgan, I. R.; Proctor, A. J. A simple oxidative procedure for the removal of ruthenium residues Tetrahedron Lett. 2010, 51, 638-640. A very simple procedure was described recently by David Knight and coworkers for the removal of ruthenium after metathesis reactions. The process involves simply stirring the crude metathesis reaction solution with excess […]

ortho-Tolyl 2nd Generation Grubbs Catalyst

ortho-Tolyl 2nd Generation Grubbs Catalyst1 (Ph = phenyl) – CAS#: [927429-60-5] – FW: 793.28 – Color: Brown – Initiation temperature: >20 °C Process Strengths Weaknesses CM -hindered alpha olefins -trisubstituted olefins RCM -sterically hindered di- and tri-substituted olefins -tetrasubstituted olefins     This catalyst was the product of a rational design effort to make catalysts […]

Functional Group Tolerance/Protecting Group Strategy

The Grubbs catalyst and all of its brothers and sisters are tolerant of most organic functional groups, but there are some bad actors to avoid… Strong Lewis bases can coordinate to the catalyst and de-activate it. Try to avoid (or protect) phosphines, thiols/sulfides, basic unhindered amines, pyridines, ureas, isonitriles, etc. The easiest way to protect […]

ISOM XIX Date & Location Announced

The Organizing Committee has just confirmed that the 19th International Symposium on Olefin Metathesis and Related Chemistry (ISOM XIX) will take place in Rennes, Bretagne, France, from July 10 to July 15, 2011. An ISOM conference is held every two years in varied locations across the world to cover the latest developments in olefin metathesis. […]

Polymer Scrambling by Macromolecular Olefin Cross-metathesis

Otsuka, H.; Muta, T.; Sakada, M.; Maeda, T.; Takahara, A. Scrambling reaction between polymers prepared by step-growth and chain-growth polymerizations: macromolecular cross-metathesis between 1,4-polybutadiene and olefin-containing polyester Chem. Commun., 2009, 1073-1075. Each polymerization method tends to offer its own rules and limitations for control of polymer architecture, but Otsuka and Takahara recently published an interesting […]

2nd Generation Grubbs Dimethylvinyl Alkylidene Catalyst

2nd Generation Grubbs Dimethylvinyl Alkylidene Catalyst (PCy3 = tricyclohexylphosphine) – CAS#: [253688-91-4] – FW: 826.97 – Color: Brown – Initiation temperature: >50 °C Process Strengths Weaknesses CM -Synthesis of 1,2-disubstituted olefins from terminal olefins-Ethenolysis of internal olefins to make terminal olefins-ADMET of unhindered terminal olefins -Formation of trisubstituted olefins-Electron-deficient substrates-Hindered substrates RCM -Synthesis of 1,2-disubstituted […]