Molybdenum and Tungsten Alkylidenes

Schrock R. R. Living ring-opening metathesis polymerization catalyzed by well-characterized transition-metal alkylidene complexes. Acc. Chem. Res. 1990, 23, 158. The “living” polymerizations possible with well-defined molybdenum and tungsten olefin metathesis catalysts are presented in this 1990 review article from Richard Schrock. Focusing mostly on ring-opening metathesis polymerization of norbornenes and norbornadienes, Schrock offers a concise […]

1st Generation Hoveyda Catalyst

1stGeneration Hoveyda Catalyst1 (PCy3 = tricyclohexylphosphine) –  CAS#: [203714-71-0] –  FW: 600.61 –  Color: Brown –  Initiation temperature: >0 °C Process Strengths Weaknesses CM2 -Synthesis of 1,2-disubstituted olefins from terminal olefins -Ethenolysis of internal olefins to make terminal olefins -Formation of trisubstituted olefins -Electron-deficient substrates-Hindered substrates RCM -Synthesis of 1,2-disubstituted olefins -Typically forms the kinetic […]

Metathesis & Peach Twig Borer Pheromone

Insects find each other to mate by sense of smell, and their chemical signaling pheromones. Adding pheromones to a field can be used as an alternative to pesticides by confusing male insects and preventing mating. While this practice holds promise as an environmentally friendly pest control method, a critical limiting factor is cost. Extracting natural […]

Method for Phosphine Exchange in Grubbs Catalysts

Sanford, M. S.; Love, J. A.; Grubbs, R. H.; A Versatile Precursor for the Synthesis of New Ruthenium Olefin Metathesis Catalysts Organometallics, 2001, 20, 5314 The ubiquitous 1st generation Grubbs catalyst, (PCy3)2Cl2Ru=CHPh, has been utilized for the synthesis of natural products, small molecules, and polymeric materials via olefin metathesis methodologies. In addition, the catalyst has […]

Effect of Temperature on Olefin Metathesis Reactions

As is the case with many chemical reactions, temperature can be both friend and foe.  Heating a reaction will invariably make it go faster, but can also increase the rate of side reactions and decomposition. For ruthenium catalyzed olefin metathesis reactions, choosing the right temperature for a reaction invariably comes down to trial and error. […]

Azepine Synthesis by RCM: SB-462795

Wang, H.; Matsuhashi, H.; Doan, B. S.; Goodman, S. N.; Ouyang, X.; Clark, W. M., Jr. Large-scale synthesis of SB-462795, a cathepsin K inhibitor: the RCM-based approaches. Tetrahedron 2009, 65, 6291 (and references therein). The GlaxoSmithKline process group has a number of reports on their body of work in which they developed an efficient process […]

Study on the Mechanism of Grubbs Catalysts

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 of previous publications, this 2001 paper from the Grubbs group was the first to report in-depth […]

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 stability in solution RCM -Activates at low temperatures ROMP -Provides narrow polydispersity materials -Will create a rapid exotherm w/ strained olefin   […]

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, 250-254. Any conversation about olefin metathesis in the pharmaceutical world has to include the work out of […]