Enantioselective Alkylation And Alkynylation Of Aldehydes Catalyzed By Polymer Supported And Silica-Immobilized Titanium (IV) Complexes Of Amino Alcohols

The design and synthesis of some novel silica-immobilized and polymer supported chiral amino alcohols were mainly discussed in this dissertation. We also discuss in detail the asymmetric addition of diethylzinc to benzaldehyde catalyzed by silica-immobilized Ti(lV) complex of N-sulfonylated amino alcohol and the enantioselective addition of phenylacetylene to aldehydes catalyzed by silica-immobilized and polymer supported titanium(IV) complexes ofβ-hydroxyamides.1. The first use of silica-immobilized Ti(IV) complexes of N-sulfonylated amino alcohols as a catalyst for the asymmetric addition of diethylzinc to benzaldehyde is reported in this part. A good yield (95%) and enantioselectivity (80%) were successfully obtained through a series of optimization studies. The use of titanium tetraisopropoxide is necessary to obtain high yields and enantioselectivity for this silica-immobilized catalytic system. After the restoring procedure, silica-immobilized catalyst can be used in multiple runs (up to 10 times) without loss of enantioselectivity.2. Same as part 1, the first use of silica-immobilized titanium(IV) complex ofβ-hydroxyamide as a catalyst for the asymmetric addition of phenylacetylene to aromatic aldehydes is reported in this part. High yields (84-95 %) and good enantioselectivities (69-81 %) were successfully achieved. After the restoring procedure, silica-immobilized ligand 5 can be used in multiple runs (up to 5 times) without serious loss of enantioselectivity.3. A series of polymer supported chiralβ-hydroxyamides and polymer supported C₂ symmetricβ-hydroxyamides have been synthesized and successfully used for the enantioselective addition of phenylacetylene to aldehydes. High yields (up to 94%) and good enantioselectivity (up to 93%) were achieved by using polymer supported 4.4a. It is suitable not only for aromatic aldehydes but also aliphatic ones.