Olefin metathesis organometallic catalysts

J. C. Conrad, D. Amoroso, P. Czechura, G. P. A. Yap, andD. E. Fogg, The First Highly Active, Halide-Free Ruthenium Catalyst for Olefin Metathesis, Organometallics 22, 3634-3636 (2003). 

The outstanding performances of five-membered NHC ligands in organometallic chemistry and catalysis prompted Grubbs and co-workers to develop a novel stable four-membered NHC [64]. Following their interest in developing new ruthenium olefin metathesis catalysts, they synthesised and fully characterised complex 51 to study the impact of the architecturally unique NHC ligand on the activity of the Ru-based catalyst [65] (Fig. 3.20). In the RCM of 1 at 40°C in CH Cl with 51 (5 mol% catalyst), the reaction reached completion within 20 min, whereas less than 10 min are required for standard catalysts 14 and 16. It should be noted that catalysts 14 and 16 are able to complete the RCM of 1 with only 1 mol% catalyst at 30°C. 

The tris-neopentyl Mo(VI) nitride, Mo(-CH2- Bu)3(=N) [134], reacts with surface silanols of silica to yield the tris-neopentyl derivative intermediate [(=SiO)Mo (-CH2- Bu)3(=NH)] followed by reductive elimination of neopentane, as indicated by labeling studies from labeled starting organometallic complex, to yield the final imido neopentylideneneopentyl monosiloxy complex [(=SiO)Mo(=CH- Bu)(-CH2 - Bu)(=NH)] [135]. The surface-bound neopentylidene Mo(VI) complex is an active olefin metathesis catalyst [135]. Improved synthesis of the same surface complex with higher catalytic activity by benzene impregnation rather than dichlorometh-ane on silica dehydroxylated at 700 °C has been reported [136],... 

T. M. Tmka and R. H. Grubbs, The Development of L2X2Ru=CHR Olefin Metathesis Catalysts An Organometallic Success Story, Acc. Chem. Res. 2001, 34, 18. 

B. Mohr, D.M. Lynn, and R.H. Grubbs, Synthesis of water-soluble, aliphatic phosphines and their application to well-defined ruthenium olefin metathesis catalysts, Organometallics, 15(20) 4317 4325,1996. 

Chabanas, M., Baudouin, A., Coperet, C. and Basset, J.-M. (2001) A highly active well-defined rhenium heterogeneous catalyst for olefin metathesis prepared via surface organometallic chemistry. J. Am. Chem. Soc., 123, 2062. 

Burdett, K.A., L.D. Harris, P. Margl, B.R. Maughon, T. Mokhtar-Zadeh, P.C. Saucier and E.P. Wasserman, Renewable Monomer Feedstocks Via Olefin Metathesis Fundamental Mechanistic Studies of Methyl Oleate Ethenolysis with the First-Generation Grubbs Catalyst, Organometallics, 23, 2027-2047 (2004). 

C. Coperet, and J.-M. Basset, Strategies to Immobilize Well-Defined Olefin Metathesis Catalysts Supported Homogeneous Catalysis vs. Surface Organometallic Chemistry, Adv. Synth. Catal. 349, 78-92 (2007). 

Vougioukalakis GC, Grubbs RH. Ruthenium olefin metathesis catalysts bearing an N-lluorophenyl-N-mesityl-substituted un-symmetrical N-heterocycUc carbene. Organometallics 2007 26 2469-2472. 

Jafarpour, L., Hillier, A. C., Nolan, S. P. Improved One-Pot Synthesis of Second-Generation Ruthenium Olefin Metathesis Catalysts. Organometallics 2002, 21,442-444. 

Cundari, T. R., Gordon, M. S. Theoretical investigations of olefin metathesis catalysts. Organometallics 902,11, 55-63. 

Tmka TM, Grubbs RH (2001) The development of L2X2Ru=CHR olefin metathesis catalysts an organometallic success story. Acc Chem Res 34 18-29... 

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