Iron catalysts ligand design

The synthesis and properties of these catalysts will be discussed in more detail below but first some aspects of the structures will be discussed to emphasize important ligand design features for iron-catalyzed hydrogenation processes. 

K. R. and Collins, T.J. (1998) Designing ligands to achieve robust oxidation catalysts. Iron based systems. Coord. Chem. Rev., 174, 361. 

Naruta et al. [225, 226] designed the twin-coronet porphyrin ligands (62) and (63) with binaphthyl derivatives as chiral substituents (Figure 13). Each face of the macrocycle is occupied by two binaphthyl units and the ligand has C2 symmetry. Iron complexes of these compounds can be very effective catalysts in the epoxidation of electron-deficient alkenes. Thus, nitro-substituted styrenes are readily epoxidized in 76-96% ee [226]. The degree of enantioselectivity can be explained on the basis of electronic interactions between the substrate aromatic ring and the chiral substituents rather than on the basis of steric interactions. 

Morris, R. H. Exploiting metal-ligand bifunctional reactions in the design of iron asymmetric hydrogenation catalysts. Acc. Chem. Res. 2015,48,1494-1502. 

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