Spirobiindane ligands

Cobalt(II) complexes prepared in situ from (AcO Co and two novel chiral spiro nitrogen-containing ligands, 7,7/-bis(2-pyridinecarboxamido)-l,l/-spirobiindane (SIPAD) and 7,7/-bis(2-quinolinecarboxamido)-l,l/-spirobiindane (SIQAD), are efficient cata- lysts for the asymmetric Michael addition of malonates to chalcone derivatives. The alkylation products were obtained in high yields with moderate enantioselectives.169... 

In 2002, Zhou and coworkers designed and synthesized a new type of spiro phosphoamidites 1 based on spirobiindane backbone [20]. These spiro monopho sphoramidite ligands 1, especially SIPHOS (la), showed high enantioselectivities (up to 99.7% ee) in the rhodium catalyzed asymmetric hydrogenation of arylenamides (Scheme 8.4) [15]. The reaction was performed under typical conditions with rhodium catalyst, usually produced in situ from [Rh(COD)2 BP.i with 2 equiv of... 

The high rigidity is the key feature of the chiral spirobiindane ligands, which exhibited special advantages in many asymmetric reactions. One example is the Cu complex of chiral spiro bisoxazoline ligand (S, S,S)-23a (R=Ph). Zhu et al. [33] analyzed the X-ray structures of Cu(I)-(5, 5,5)-23a with various anions (PF, C10 , and BArp). All the complexes have an unexpected binuclear Cu structure, as shown... 

Figures Chiral ligands with I, I -spirobiindane backbone...

The Zhou group synthesized a series of C2-symmetric chiral bisoxazo-line ligands (SpiroBOX) featuring a spirobiindane scaffold and tested these ligands in the enantioselective Cu-catalyzed allylic oxidation of cyclic alkenes with tert-butyl perbenzoate as the oxidant. The desired allylic benzoate was obtained in 58% yield and 70% ee with (7 ,S, S )-L35 as the ligand. 

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