Sanford M. S.; Love J. A.; Grubbs R. H. Mechanism and activity of ruthenium olefin metathesis catalysts. J. Am. Chem. Soc. 2001, 123, 6543-6554. Although the mechanism of 1st generation ruthenium metathesis catalysts had been explored in a number … [Continue reading]
Fast-initiating Grubbs Catalyst
Fast-initiating Grubbs Catalyst1 (Ph = phenyl; Mes = mesityl) - CAS#: [900169-53-1] - FW: 884 - Color: Green - Initiation temperature: <0 °C Process Strengths Weaknesses CM2 -Efficient CM w/ acrylonitrile -Poor thermal … [Continue reading]
Macrocycles in Medicine: BILN 2061
Farina, V.; Shu, C.; Zeng, X.; Wei, X., Han, Z.; Yee, N. K.; Senanayake, C. H. Second-generation process for the HCV protease inhibitor BILN 2061: a greener approach to Ru-catalyzed ring-closing metathesis. Org. Process Res. Dev. 2009, 13, … [Continue reading]
Molybdenum Catalyst with a Stereogeneic Metal Center
Flook, M. M.; Jiang, A. J.; Schrock, R. R.; Müller, P.; Hoveyda, A. H. Z-Selective olefin metathesis processes catalyzed by a molybdenum hexaisopropylterphenoxide monopyrrolide complex. J. Am. Chem. Soc. 2009, 131, 7962-7963. There aren’t many … [Continue reading]
Cross Metathesis Reaction Planning
There’s nothing more frustrating to a synthetic chemist than a reversible reaction. We incur great expense to prepare reactive reagents (MeMgBr, LiAlH4, Br2, PhI(OAc)2, etc.) that do their thing and then just stand by and watch after they’re done. I … [Continue reading]
Selectivity in Olefin Cross Metathesis
Chatterjee, A. K.; Choi, T.-L.; Sanders, D. P.; Grubbs, R. H. A general model for selectivity in olefin cross metathesis. J. Am. Chem. Soc., 2003, 125, 11360-11370. When well-defined olefin metathesis catalysts started to come on scene, the … [Continue reading]
Mechanism of Ring Closing Metathesis: Oligomers as Intermediates
Conrad, J. C.; Eelman, M. D.; Silva, J. A. D.; Monfette, S.; Parnas, H. H.; Snelgrove, J. L.; Fogg, D. E. Oligomers as Intermediates in Ring-Closing Metathesis. J. Am. Chem. Soc. 2007, 129, 1024-1025. Reading this communication changed the way I … [Continue reading]
2nd Generation Hoveyda Catalyst
2ndGeneration Hoveyda Catalyst1 - CAS#: [301224-40-8] - FW: 626.62 - Color: Green - Initiation temperature: >0 °C Process Strengths Weaknesses CM2 -Compatible with most olefins, including highly electron-deficient (i.e. … [Continue reading]
Grubbs Triblock Copolymers
Careful combination of multiple polymerization mechanisms can generate truly unique architectures. Incorporation of chain-segments generated by metathesis polymerizations have been explored by a number of researchers (particularly the Matyjaszewski … [Continue reading]
Identifying the Best Ruthenium Catalyst
Bieniek, M.; Michrowska, A.; Usanov, D. L.; Grela, K. In an Attempt to Provide a User’s Guide to the Galaxy of Benzylidene, Alkoxybenzylidene, and Indenylidene Ruthenium Olefin Metathesis Catalysts. Chem. Eur. J. 2008, 14, 806-818. There are a … [Continue reading]
Inhibiting Olefin Isomerization
Olefin isomerization/migration can be an annoying side reaction of olefin metathesis, in no small part because the side products are usually difficult to separate from the desired product. The isomerization is catalyzed by metal hydride species … [Continue reading]