Binol/Titanium isopropoxide

BITIP Binol/Titanium isopropoxide Ti(iPrO)4 / BINOL... 

Mikami and co-workers16-19 have done extensive work for developing catalysts for the asymmetric carbonyl-ene reaction. Excellent enantioselectivites are accessible with the binol-titanium catalyst 17 (Equation (10)) for the condensation of 2-methyl butadiene (R1 = vinyl) and glyoxalates (binol = l,T-binaphthalene-2,2 -diol).16 The products were further manipulated toward the total synthesis of (i )-(-)-ipsdienol. The oxo-titanium species 18 also provides excellent enantioselectivity in the coupling of a-methyl styrene with methyl glyoxalate.17 Reasonable yields and good enantioselectivites are also obtained when the catalyst 19 is formed in situ from titanium isopropoxide and the binol and biphenol derivatives.18... 

Bao and co-workers also reported enantioselective ring-opening ami-nolysis of epoxide, 93, with benzylamine, 94, catalyzed by the titanium isopropoxide-BINOL-water system (BlNOL=l,l -bi-2-naphthol-96) in toluene (reaction 7.16) [66]. Titanium isopropoxide-isopropanol, 96, system also used by Kim et al. for asymmetric methallylation of ketones (reaction 7.17) with high yield and enantioselectivity [67]. 

A BINOL-salen ligand catalyses the enantioselective addition of TMSCN to aldehydes at room temperature, in the presence of titanium(IV) isopropoxide.269... 

Tridentate BINOL catalysts can be derived from titanium tetra(isopropoxide), BINOL ligands, and hindered amine bases. These catalysts have also been shown to provide good yields and ee s for the aldol reactions at low temperatures of 2-methoxypropene with several aldehydes to the P-hydroxyketones, but an acid workup of the products is required. 

Chiral Oxygen Ligands. Among the oxygen donor ligands, the BINOL-type ones are predominant (68). The parent compound and its 3,3 -dibromo-substituted derivatives form efficient catalysts with titanium and zirconium (Fig. 8). Binaphthol-modified titanium(lV) compounds are efficient catalysts for ene reactions of glyoxylic esters and olefins. The replacement of isopropoxide of the titanium precursor, TiCl2(OiPr)2, is a crucial step in the formation of the catalytic species. 

---