掌性釩錯合物為催化劑及樟腦醯胺為輔助基於不對稱合成之研究

• Main Authors: Hsu, Chu-Ting, 許筑婷
• Other Authors: Uang, Biing-Jiun
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/20213261326176146445

博士 === 國立清華大學 === 化學系 === 98 === Abstract This thesis is divided into three parts. The first and second parts deal with a series of chiral vanadium complexes that were prepared with amino alcohols, amino acids and salicylaldehyde derivatives. These chiral complexes have been utilized in the studies of asymmetric kinetic resolution of racemic sulfoxide and the synthesis of cyanohydrins. The third part deals with the application of chiral imine 100 in asymmetric tandem Michael-Aldol reaction. 1) Kinetic resolution of sulfoxide : Simple, inexpensive, preformed vanadium- Schiff base complexes were facilely prepared and used in enantioselective sulfoxidation. Kinetic resolution is observed in the oxidation of racemic sulfoxide using a combination of VO(acac)2 and ligand 36 in chloroform at 0 °C. High enantioselectivity (up to 99% ee) and reasonable yield (70%) was achieved by combining enantioselective sulfoxidation and appropriate concomitant kinetic resolution. 2) Asymmetric cyanohydrin synthesis: In the presence of amino acids and salicylaldehyde derivatives, new vanadium complexes were found to catalyse the asymmetric addition of trimethylsilyl cyanide to aldehydes. Under optimised conditions, enantioselectivities of 60–91% were obtained using 5 mol % of the catalyst. 3) Asymmetric tandem reaction: Michael addition of enolate of imine 100 derived from glycinate and ketopinic amide to ???? unsaturated esters and subsequent Mukaiyama Aldol reaction with aldehydes afforded the corresponding products 104b and 104d with 94:6 de in one pot reaction conditions. Hydrolysis of major products 104b gave multisubstituted ?? lactams and ?? lactones consisted of consecutive four stereogenic centers with high enantiomeric excesses.