| Summary: | 碩士 === 國立東華大學 === 化學系 === 96 === Abstract
The asymmetric addition of TMSCN to aldehydes was investigated. The chiral catalyst was prepared from Ti(O-i-Pr)4 and new chiral bipyrideine ligand 2-20 with (-)-α- pinene skeletons. Various temperatures, solvents and the amounts of chiral catalyst were used. The best reaction conditions are the use of CH2Cl2 as a solvent, -78 ºC and using 5 mol% of chiral catalyst. The result almost the same as reported in this lab before. Numerous aromatic aldehydes were used in the asymmetric addition of TMSCN to produce cyanohydrins, and the yields were from 40% to 85%. The enantioselectivities were from 1% to 75%, but the major enantiomers were different. The non-linear effect was investigated using this chiral bipyridine in the asymmetric addition TMSCN to aldehydes.
Synthesis of the chiral ligand derived from (+)-α-pinene was developed to aim at the asymmetric of Nozaki-Hiyama reaction. Then a novel chiral bipyrdeine ligand 3-26 was synthesized, and performed an excellent enantionselectivity in the asymmetric of Nozaki-Hiyama reaction. To optimize the best reaction condition, the reactions were played in different condition. The best reaction condition is the use of THF as a solvent, Et3N as additive base, allyl chloride as allyl source, using CrCl3 as chealating metal, and using 10 mol% of chiral catalyst. Several aromatic aldehydes were used in the asymmetric Nozaki-Hiyama reaction, and the enantioselectivities were 60% to 98%, and the yields were from 25% to 89%.
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