Monophosphite ligands

Reetz, M.T. and Mehler, G. (2000) Highly enantioselective Rh-catalyzed hydrogenation reactions based on chiral monophosphite ligands. Angew. Chem., Int. Ed., 39, 3889-3890. 

Chiral monophosphite ligands were attached to PEG and used as ligands for the Rh-catalyzed asymmetric hydrogenation of C=C double bonds [125]. The polymeric catalysts 190 and 191 performed well in the asymmetric hydrogenation of... 

Scheme8.n Asymmetric hydrogenation ofp substituted enamides with monophosphite ligands.

Table 8.2 Asymmetric hydrogenation of terminal a arylenamides 1 with chiral monophosphite ligands.

The rhodium catalyzed asymmetric hydrogenation of terminal arylenamides 7 by using monophosphite ligand 30 provided chiral N acetyl arylamines 8 with... 

Scheme 8.13 Asymmetric hydrogenation of arylenamides with PEC supported monophosphite ligands.

Similar results for the asymmetric hydrocyanation of norbornene (up to 70% yield with up to 38% ee) were obtained using an air-stable chirally modified Ni(0)L2 complex as the catalyst precursor39. The chiral (7 )-2,2 -binaphthol-derived aryl diphosphite (L1), contains three 1,1 -binaphthyl units. Its Ni(0)L2 complex is prepared from Ni(cod)2 and can be activated with trip hen ylboron39. Use of a similar chiral monophosphite ligand [L2, also derived from (/ )- 2,2 -... 

In 2005, the Zhou group applied the biindane-derived ehiral spiro phosphoramidite and phosphite ligands in the Pd-catalyzed asymmetric hydrovinylation of styrene. However, only moderate yield and enantiose-lectivity could be obtained. Recently, Muller and co-workers synthesized Cj-symmetric tris-binaphthyl monophosphite ligand L29, and used it in the Pd-catalyzed asymmetric hydrovinylation reaction. The hydrovinylation product of styrene could be obtained in 70% conversion and 92% ee (Scheme 9.12). ... 

Quinazolinap ligand. Smith and Takacs reported an efficient amide directed asymmetric hydroboration of trisubstituted alkenes using TADDOL-deffved phenyl monophosphite ligands. Demay et reported the hydroboration reaction using C2-symmetric 1,2-diphosphane ligands. Evans and Fu suggested a catalytic cycle for catalytic hydroboration, which was supported by computational studies. ... 

Rhodium complexes, formed in situ with [Rh(COD)2]BF4 and monodentate chiral spiro phosphite and phosphine ligands, catalyse the AH of both (Z)- and (E)-P-arylenamides with up to 97% ee. A library of 19 chiral binol-monophosphite ligands containing a phthalic acid secondary bis-amide group has been synthesized and screened for use in stereocontrol of rhodium-catalysed hydrogenation of several prochiral dehydroamino esters and enamides. Spectroscopic and computational studies... 

More recent key players in this area have been RajanBabu [86, 87] and Leitner [88, 89], Extensive studies by RajanBabu resulted in the identification of the optimized diaryl monophosphite ligand 156 (Equation 22) [87]. In combination with SbF " as the counterion, the nickel-catalyzed hydrovinylation of bromostyrene 155 affords the desired adduct 157 with high selectiv-ities (98% yield, 89% ee). Independent contemporary studies by Leitner,... 

Figure 4.23 Supramolecular chiral dendritic monophosphite ligands for the Rh-catalyzed asymmetric hydrogenation.

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