Chiral self-dimerization

This chapter focuses on several recent topics of novel catalyst design with metal complexes on oxide surfaces for selective catalysis, such as stQbene epoxidation, asymmetric BINOL synthesis, shape-selective aUcene hydrogenation and selective benzene-to-phenol synthesis, which have been achieved by novel strategies for the creation of active structures at oxide surfaces such as surface isolation and creation of unsaturated Ru complexes, chiral self-dimerization of supported V complexes, molecular imprinting of supported Rh complexes, and in situ synthesis of Re clusters in zeolite pores (Figure 10.1). 

Chiral Self-Dimerization ofV Complexes on a S/O2 Surface for Asymmetric Catalysis 383... 

Chiral Self-Dimerization of V Complexes on a SiOj Surface for Asymmetric Catalysis... 

Chiral Self-Dimerization of V-Schiff-Base Monomer Complexes on Si02... 

Scheme 10.2 Chiral self-dimerization of V-Schiff-base monomer complexes on Si02. Two vanadium monomers are dimerized through two sets of hydrogen bonds between Ph-OH and COO.

Notably, the enantioselectivity of the coupUng reaction is determined by the chiral conformation on the V center rather than the chirality of the Schiff-base ligands. The chirality of the ligands affects stericaUy the chiral self-dimerization... 

Chiral Self-Dimerization of Vanadium Schiff-Base Complexes on Si02 and Their Catalytic Performances lor Asymmetric Oxidative Coupling of 2-Naphthol... 

BINOL and its derivatives have been utilized as versatile chiral sources for asymmetric catalysis, and efficient catalysts for their syntheses are, ultimately, required in many chemical fields [39-42]. The oxidative coupling of 2-naphthols is a direct synthesis of BINOL derivatives [43, 44], and some transition metals such as copper [45, 46], iron [46, 47] and manganese [48] are known as active metals for the reaction. However, few studies on homogeneous metal complexes have been reported for the asymmetric coupling of 2-naphthols [49-56]. The chiral self-dimerized V dimers on Si02 is the first heterogeneous catalyst for the asymmetric oxidative coupling of 2-naphthol. 

Figure 2.1 Chiral self-dimerization of V Schiff-base monomers (1) on Si02.

The chiral self-dimerization oftheV complex precursors at the Si02 surface produced a unique reaction space for the selective oxidation. 

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