Rhodium catalyzed asymmetric hydrogenation

In 1968,Horner et al. [22] and Knowles and Sabacky [23] independently demonstrated that low but definite enantiomeric excesses (up to 15% ee) were produced in the rhodium-catalyzed asymmetric hydrogenation of simple alkenes using methylpropylphenylphosphine 7 as chiral ligand (Scheme 1). 

An unusual carbene-thioether hybrid ligand 174 was synthesized and applied in the rhodium-catalyzed asymmetric hydrogenation of dimethyl itaconate by Chung and co-workers however, the selectivity and activity were low (Table 27.7, entry 34) [135]. 

Modification of the electronic and steric properties of BINAP, BIPHEMP, and MeO-BI-PHEP led to the development of new efficient atropisomeric ligands. Although most of them are efficient for ruthenium-catalyzed asymmetric hydrogenation [3], Zhang et al. have recently reported an ortho-substituted BIPHEP ligand, o-Ph-HexaMeO-BIPHEP, for the rhodium-catalyzed asymmetric hydrogenation of cyclic enamides (Scheme 1.2) [31]. 

Recently, many effective chiral bisphosphane hgands with a ferrocene backbone have been developed (Scheme 1.4). Ito has successfully developed a series of traits-chelating bisphosphane hgands, TRAPs, which are highly selective for rhodium-catalyzed asymmetric hydrogenation [46]. 

Applications of Chiral Phosphorous Ligands in Rhodium-Catalyzed Asymmetric Hydrogenation... 

Rhodium-Catalyzed Asymmetric Hydrogenation of Functionalized Alkenes... 

I -BINAPHTHYL AS A LIGAND FOR RHODIUM-CATALYZED ASYMMETRIC HYDROGENATION. 36... 

DIMETHYLPHENYL)PHOSPHINO]-3,3 -BIPYRIDINE [(R)-Xyl-P-Phos] AS A LIGAND FOR RHODIUM-CATALYZED ASYMMETRIC HYDROGENATION OF a-DEHYDROAMINO ACIDS... 

Rhodium-catalyzed asymmetric hydrogenation of dehydroamino acids and en-amides is an efficient method for the preparation of optically active amino acids and... 

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