Ferrocenyl phosphine ligands

Ph2SiH2,THF, l%RhCl(OTD)2L chiral ferrocenyl phosphine ligand... 

Enantioselective Hydrosilylation Employing Chiral Ferrocenyl Phosphine Ligands 285... 

Kumada s group (252, 255, 256) has synthesized a range of ferrocenyl-phosphine ligands (28, 29) initially for use in asymmetric hydrosilylation. 

Kumada (44) showed that chiral ferrocenyl phosphine ligands on rhodium gave good optical yields of carbinols from prochiral ketones. 

Many attempts have been made to develop novel nonracemic ferrocenyl phosphine derivatives as asymmetric hydrogenation catalysts. Interested readers will find the design and synthesis of these chiral ferrocenyl phosphine ligands in a recent review by Richards and Locke.286... 

Tetrahydrobis(benzofuran) is produced by a tandem cyclization reaction from the bis-vinyl ether on reaction with catalytic quantities of rhodium(l) salts in the presence of electron-rich phosphine ligands <20030L1301>. Thus, employing 10mol% of [RhCl(coe)2]2 with 20mol% of a dicyclohexyl ferrocenyl phosphine ligand produces the bis-cyclized product (coe = cyclooctene Equation 67). 

Kaneko et al. reported the preparation of the key intermediate (-F)-12 of (—)-HA via the asymmetric Pd-catalyzed bicycloannulation of the p-keto ester 2 with 2-methylene-1,3-propanediol diacetate 11 (Scheme 4-8). The chiral ferrocenyl-phosphine ligand 13 gave 64% ee enantioselectivity. 

Other means of immobilizing ferrocenyl phosphine ligands inclnde covalent see Covalent Bonds) attachment to either sihca gel see Silica) or solid snpport poly(ethylene glycol) (TantaGel), or confinement within mesoporons MCM-41. " ... 

Very recently in a joint effort from industry and academia an improved Pd catalyst system based on bidentate ferrocenyl phosphine ligands was developed that enables the carbonylation of electron-deficient, electronically neutral, and electron-rich aryl chlorides in good to excellent yield [58]. The new catalyst represents a substantial improvement in efficiency, utility and practicability for... 

Complexes of different dendrimers with rhodium that contained ferrocenyl phosphine ligands on the surface, 52-53, were also active in hydrogenation. They catalyzed dimethylacetone hydrogenation at an optical selectivity of 98%, which is comparable to the selectivity of a low molecular weight analogue [113, 123, 124]. 

Abstract Chiral ferrocenyl phosphine ligands are certainly one of the most developed and successful classes of chiral ligands used in asymmetric catalysis. The literature describing their synthetic and coordination chemistry, as well as their metal-mediated applications in the field of catalysis, is extremely rich and varied. Moreover, they represent a rare example in which enantioselective chemical catalysts were used in industrial processes. The present chapter provides an account of the planar-chiral ferrocene ligands developed in the Authors laboratory, including their coordination chemistry with various metals as well as their use in different asymmetric catalytic reactions (allylic substitution, Suzuki coupling, methoxycarbonylation of alkenes, hydrogenation of ketones). 

Scheme 20. Example of synthesis of a ferrocenyl-based P-chirogenic phosphine ligand...

In addition, Peruzzini et al. developed, in 2007, iridium complexes of planar-chiral ferrocenyl phosphine-thioether ligands that were tested in the hydrogenation of simple alkyl aryl ketones.These complexes were diastereoselec-tively generated in high yields (85-90%) by addition of the corresponding... 

Scheme 8.33 Hydrogenations of alkyl aryl ketones with ferrocenyl phosphine-thioether ligands.

Chiral ruthenocenyl phosphine ligands offer no great advantages for hydroboration of styrene relative to the ferrocenyl analogues.56... 

Rh complexes with ChiraPhos, PyrPhos, or ferrocenyl phosphines lacking amino alkyl side chains (such as BPPFA) are much less active toward tetrasubstituted olefins. Table 6-1 shows that in asymmetric hydrogenations catalyzed by 5a-d, the coordinated Rh complex exerts high selectivity on various substrates. It is postulated that the terminal amino group in the ligand forms an ammonium carboxylate with the olefinic substrates and attracts the substrate to the coordination site of the catalyst to facilitate the hydrogenation. 

The research group of Van Leeuwen has focused on catalysis at the core of a carbosilane dendrimer in an effort to be able to control stereoselectivity [10]. To this end, a ferrocenyl diphosphine backbone was functionalized with different generations of carbosilane dendrons producing a series of dendrimer phosphine ligands with an increasing steric demand (see 7 for an example, Scheme 6). In situ... 

Another interesting family of phosphine ligands that has been applied to this coupling reaction is the ferrocenyl-phosphines. Some air-stable examples are showed in Figure 3. Compound 20 has been used for the coupling of aryl chlorides in combination with a Pd(0) source,while 21 gave excellent results for the coupling of a variety of aryl... 

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