Olefin metathesis tricyclohexylphosphine

A closer look on the history of the development of catalyst 52 shows that this class of compounds was to some degree predestined for the application of NHCs. Complex 51 containing triphenylphosphines is an active catalyst for olefin metathesis. However, the substitution of the triphenylphosphines by more electron-donating and sterically more demanding tricyclohexylphosphines is accompanied by a significantly increased stability and catalytic performance " Thus, complexes of type 53 58,2S5 logical development with respect... 

Recently, it was shown that bis(tricyclohexylphosphine)benzyhdene ruthenium dichloride (101) [120, 121] is also capable of catalyzing olefin metathesis on a sohd support [122], Thus, performing the reaction as ring-closing metathesis offers an-... 

Ring D (see Scheme 15) has been successfully appended to the tricyclic core by an olefin metathesis reaction (147). Treatment of 177, prepared largely by the method described in Scheme 11, with the ruthenium complex 178 (Cy3P = tricyclohexylphosphine) resulted in the ABCD ring system of the manzamines. 

After having observed that the most active ruthenium-based catalyst systems for olefin metathesis also displayed a high efficiency in atom transfer radical polymerisation, we then became interested in comparing the role of the catalyst in those two different reaction pathways. Ruthenium alkylidene complexes 4-6 are unsaturated 16-electron species which formally allow carbon-halogen bond activation to form a 17-electron ruthenium(III) intermediate. Our preliminary results indicate that polymerisations occur through a pathway in which both tricyclohexylphosphine and/or imidazolin-2-ylidene ligands remain bound to the metal centre. 

Olefin Metathesis. Olefin metathesis is one of the most important and powerful reactions in organic synthesis. Many of the catalysts used for the reaction contain at least one tricyclohexylphosphine ligand, the so-called Grubbs type 1(1) and Grubbs... 

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