Olefinations 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... 

Significant advances in organonickel chemistry followed the discovery of frtzws,fraws,fraws-(l,5,9-cyclododecatriene)nickel, Ni(cdt), and bis(l,5-cycloocta-diene)nickel Ni(cod)2 by Wilke et. al.1 In these and related compounds, in which only olefinic ligands are bonded to the nickel, the metal is especially reactive both in the synthesis of other compounds and in catalytic behavior. Extension of this chemistry to palladium and to platinum has hitherto been inhibited by the lack of convenient synthetic routes to zero-valent complexes of these metals in which mono- or diolefins are the only ligands. Here we described the synthesis of bis(l,5-cyclooctadiene)platinum, tris(ethylene)-platinum, and bis(ethylene)(tricyclohexylphosphine)platinum. The compound Pt(cod)2 (cod = 1,5-cyclooctadiene) was first reported by Muller and Goser,2 who prepared it by the following reaction sequence ... 

Norbornene polymers or polymers from dicyclopentadiene, respectively, may be formed by the interaction of a cyclic olefin with a ROMP catalyst. Increased reinforcement density provides for extremely high stiffness and strength in poly(norbornene) composites. As catalyst, Phenylmethylene-bis-(tricyclohexylphosphine) ruthenium dichloride is used (30). 

The coupling of the unsubstituted carbon atom of the mono-olefin with the Cs chain, which was observed in the co-oligomerization of styrene with butadiene, and of acrylic esters with butadiene, is not, however, a general phenomenon. For example, the co-oligomerization of 1-decene with butadiene using nickel-tricyclohexylphosphine as catalyst leads (after... 

In ROMP cyclic olefins are polymerized to polyalkenamers. Both 1 and 3 can be used for this reaction, but catalyst 3 was found to be significantly more efficient for the polymerization of cyclooctene derivatives (Eq. 13) [30]. Polymerization commences with initiation of the catalyst through dissociation of a neutral ligand such as a tricyclohexylphosphine for 1 and 3 (see... 

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. 

The olefin complexes of iron, nickel, rhodium, and iridium described in this chapter have found broad application in the synthesis of phosphine, phosphite, and carbonyl derivatives of these metals. In Chapter Two, the synthesis of another labile olefin complex, (ethylene)bis(tricyclohexylphosphine)nickel, is described as an initial step in synthesis of a complex of dinitrogen. 

The C—C bond formation in these complexes is reversible. Treatment of the butadiene or isoprene derivatives with molten triphenylphosphine leads to diene evolution, in moderate yields, but reductive coupling of the M—C bonds occurs when the complexes are reacted with CO at low T since 4-vinylcyclohexene is formed . An unstable olefin complex can be formed from divinylcyclobutane and (cyclododecatriene)Ni(tricyclohexylphosphine) that liberates divinylcyclobutane when... 

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. 

Scheme 13 Rutheniuin(0)-catalyzed C-C coupling of diols with a-olefins via transfer hydrogenation. Yields are of material isolated by flash chromatography on silica gel. C10H15CO2H = 1-adamantanecarboxylic acid. PCys = tricyclohexylphosphine...

Silver(I) carbonate functioned as an co-oxidant with TEMPO. Tricyclohexylphosphine was employed to suppress homocoupling between heteroarenes. Substituted thiophenes, furans, and indoles could be selectively olefinated (C5-alkenylation for thiophenes and furans, C3-alkenylation for indoles, E/Z <99 1). Unsubstituted thiophenes produced poor yields (24%) however, formyl, acetyl, and ketyl substituents were well tolerated. For electron-deficient substrates, tricyclohexylphosphine was reduced to 10 mol % to achieve good conversions. A variety of ketones could be employed using 2-methyl thiophene as a coupling partner. 

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