Ferrocenyl phosphines

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

B. (2000) Gold and Silver Complexes with the Ferrocenyl Phosphine FcCH2PPh2 [Fc = (Tl5-C5H5)Fe(h5-C5H4)]. Inorganic Chemistry, 39(4), 680-687. 

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.

Enantioselective Hydrosilylation Employing Chiral Ferrocenyl Phosphine Ligands 285... 

Itaconic acids are reduced in very high enantiomeric excesses (>97%) with Rh-TangPhos catalysts 658 Itaconic acid is reduced in 99.5% ee with the sugar-derived ferrocenyl phosphine 123.659... 

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. 

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. 

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... 

Tris(ferrocenyl)phosphine, FCjP, undergoes oxidations of each ferrocenyl moiety in three different steps. This means that there is the same through-bond charge delocalization, but with some participation of the phosphorus atom (Barriere et al. 2005). 

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). 

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... 

Scheme 11 Van Leeuwen s core-functionalized ferrocenyl-phosphine carbosilane den-drimers used as ligands in palladium-catalyzed allylic alkylation reactions...

Scheme 33 Coordination chemistry of chiral ferrocenyl phosphine/sulfide-imidazolium salts...

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. 

The tremendous growth of the use of enantiomerically pure ligands in homogeneous asymmetric catalysis as led to significant efforts to immobilize the active catalysts in order to recycle them or prevent (or minimize) metal leaching into products. Both achiral and chiral ferrocenyl phosphines are among those catalysts that have been utilized in this context, and detailed descriptions of this research have appeared in a number of review articles. " " ... 

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. " ... 

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