Ferrocene-based diphosphines

Fig. 25.5 Generic structures and names or numbers of ferrocene-based diphosphines with P bound to both Cp rings.

H.U. Blaser, M. Lotz, F. Spindler, "Asymmetric Catalytic Hydrogenation Reactions with Ferrocene Based Diphosphine Ligands" in Handbook of Chiral Chemicals, 2nd Edition, D. J. Ager (Ed.), CRC Press, Boca Raton 2005... 

The benchmark ligand for this reaction, which is also the one used for the industrial-scale reaction, is the Xyliphos ligand, a ferrocene-based diphosphine bearing the same stereochemical features and substitution pattern as ligand... 

Subsequently, Landis studied the coordination of the ferrocene-based diphosphine-benzoxaborolidine ligands 53 with the aim of supporting secondary interactions between the pendant Lewis acid and an external Lewis base.63 Stable platinum complexes 63a-c were formed by reacting... 

Asymmetric hydroboration of prochiral alkenes has been achieved using transition metal catalysts and chiral phosphines as ligands to obtain enantiomerically pure alkyl boronates <1997CC173>. Catalysts such as Rh(COD)2+BF4 , Rh(COD)2+Cl, Rh+BF4 , etc., in combination with chiral phosphines like DIOP 71, BINAP 72, CHIRAPHOS 73, DIPAMP 74, BDPP 75, ferrocene-based diphosphines 76<1999TL4977>, etc., have been employed for the asymmetric hydroboration of prochiral alkenes with moderate to high ee (DIOP = 2,3-0-isopropylidene-2,3-dihydroxy-l,4-bis(diphenylphosphino)butane BINAP = 2,2-bis(diphenyl-phos-phanyl)-l,1-binaphthyl CHIRAPHOS = 2,3-bis(diphenylphosphino)butane DIPAMP = l,2-bis[(2-methoxyphe-nyl)phenylphosphino]ethane BDPP = 2,4-bis(diphenylphosphino)pentane). 

Asymmetric Catalytic Hydrogenation Reactions with Ferrocene-Based Diphosphine Ligands... 

In 1998, Hamann and Hartwig reported that electron-rich, ferrocene-based diphosphines such as 13 allowed for the coupling of cyclic amines with aryl chlorides [72,73]. The known ligand 13 proved to be most generally useful for this transformation, Eq. (42). The 13/Pd-catalyzed arylation reaction was performed with cyclic amines as well primary amines, however, no reactions with acyclic secondary amines were reported. 

Hartwig reported that ferrocene-based diphosphine 13 catalyzes the arylation of aniline at room temperature, Eq. (91) [72]. Additionally, the (f-BuljP/Pd-based system effects the room-temperatuxe condensation of anilines and aryl bromides. However, the (f-BuljP/Pd-catalyst is considerably more active [50]. While the reaction with 4-bromotoluene and anihne proceeded in 20 h using 5 mol% 15/Pd(dba)2, the reaction between bromoben-zene and aniline was complete in 1 h using only 1 mol% of the (f-BuljP-derived catalyst. 

Hartwig and co-workers reported that several ferrocene-based diphosphines are useful in the arylation of primary amines with aryl chlorides [72]. Known ligands 20 [104] and 21 [105] are particularly effective in the coupling of chloroarenes and primary aliphatic amines, Eq. (102). 

FIGURE 29.9. Selection of ferrocene-based chiral ligands (A) ferrocene-based diphosphines with planar chirality only (B) bidentate ferrocene-based ligands with ntixed planar and central chirality and (C) ligands with planar and axial chirality as well as planar, central, and axial chirahty. 

Blaser H-U, Lotz M, Spinder R Asymmetric catalytic hydrogenation reactions with ferrocene-based diphosphine ligands. 

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