摘要
The development of privileged chiral architectures,which are versatile for various chiral ligands or organocatalysts preparation with superior performance in a variety of organic transformations,has significantly pushed forward the advancement of asymmetric catalysis.However,only a few scaffolds could be seen as privileged chiral backbones,including BINOL-,SPINOL-,TADDOL-,quinine-,planar chiral ferrocene-based backbones and others.111 In view of the importance of novel chiral ligand skeletons in asymmetric catalysis,our group came up with a design of Si-centered spirocyclic skeletons,which could serve as a platform for new chiral ligands and organocatalysts preparation.In term of the electronegativity of Si,the longer C-Si bond(C-Si vs.C-C:co 1.87 A vs.ca 1.53 A),bigger atomic radius(Si vs.C:111 pm vs.67 pm),and vertical configuration of Si-centered spirocycles in comparison to C-centered spirocyclic scaffolds/21 the new skeletons might lead to a different reactive behavior in asymmetric catalysis(Scheme 1A).
