Chiral Ligands for Special Substrates

In contrast to the chiral ligands discussed above, there are some individuals that exhibited the desired catalytic properties only for a particular substrate. Some of the most remarkable ones will be described in the following. 

Deoxo-Fluor = Bis(2-methoxyethyl)aminosulfur trifluoride DIEA = Diisopropylethylamlne 

Selective monosubstitution in the starting dibromide by PPh2 was realized at lowtemperatures [71]. Conversion of the second bromo substituent into the phosphorus diamide and final reaction with the diol produced the hybrid ligand. In the hydroformylation of 2,5-dihydrofuran, up to 91% ee with no isomerization was achieved, which is the best value reported to date. Noteworthy, the partially hydrogenated binaphthyl unit and the phenyl substituents in the 3,3 -positions are essential for the success of the asymmetric catalysis. Related ligands with a binaphthyl backbone, with or without Me-substituents in 3,3 -positions, resulted in poor conversions and stereoselectivities. 

The resulting alcohol was esterified with ClPPh2 to produce the corresponding phosphinite. In rhodium-catalyzed hydroformylation of methyl acrylate, the P,Af-ligand induced the formation of the branched aldehyde with 

Comparison of the Catalytic Performance of Some Privileged Ligands 

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