Azaferrocene-based ligand

Fu reported the first enantioselective arylation protocol of aldehydes 1 involving diphenylzinc as aryl source and chiral azaferrocene-based ligand 3 (Scheme 8.1 ... 

Carbonylation of azaferrocene includes a rr a rearrangement of the pyrrolyl ligand and is reversible (82IC868). The similar process under the influence of the other TT-acidic ligands [PE3, R2NPE2 (R = Me, Et), MeN(PE2)2, r-BuNC, n-PrNC, Mc2N(CH2)2NC, and PhNC)] occurs. Derivatives based on 29 are isolated. 

The lone pair in the T] -pyrrolyI ligands is the most basic site in V azolyl complexes, and is the site of protonation and electrophilic attack. Novel planar chiral catalysts have been prepared, based on the azaferrocene unit, and these complexes have been used for asymmetric nucleophilic catalysis. One example of such a complex is shown on the left in Figure 4.5. Some linked versions of azaferrocenes possessing C synunetry create an unconventional chiral environment. The ligand on the right in Figure 4.5 has been used for several asymmetric copper-catalyzed transformations. ... 

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