Spiro bisoxazoline ligands

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... 

It was found that the iron catalysts prepared in situ from FeCl -dH O and chiral Spiro bisoxazoline ligands 23 exhibited excellent enantioselectivity as well as reactivity for the insertion of O—H bonds of various saturated alcohols and allylic alcohols (Scheme 46) [111]. The catalyst Fe-(S, S,S)-23c showed higher yields and higher enantioselectivities than any other metal catalysts. 

Spiro bisoxazoline ligand (SJ-164 was efficiendy applied in the enantioselective Cu-catalyzed intramolecular insertion of carbenoids into a phenolic O-H bond (13AGE2555). 

Cu(OTf)2 in the presence of the ligand ( )-N-((naphthalen-7-yl)methylene) benzenamine and C6H5NHNH2 catalyses selective oxidation of benzylic C(sp )-H bonds to C(sp )-0 bonds with t-butyl perbenzoate (TBPB) in acetone. Cu(MeCN)4PF5 catalyses asymmetric allylic oxidation of acyclic olefins by TBPB in acetone in the presence of spiro bisoxazoline ligands (8) the product allyl esters are formed with excellent regioselectivity (>20 1 in most cases) and up to 67% ee. °°... 

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