多壁碳纳米管固载金鸡纳生物碱季铵盐类手性相转移催化剂的制备及其催化烷基化反应性能

制备了多壁碳纳米管(MWCNTs)固载的金鸡纳生物碱季铵盐类手性相转移催化剂PTC-1/MWCNTs,并用于催化N-二苯亚甲基-甘氨酸叔丁酯的不对称烷基化反应中.采用紫外-可见光谱系统研究了五种有机溶剂对PTC-1在MWCNTs上吸附和脱附的影响.结果表明,在甲苯中,MWCNTs对PTC-1的吸附率最高(53%),而在三氯甲烷中PTC-1的脱附率最低(仅为0.75%).PTC-1/MWCNTs催化剂在催化N-二苯亚甲基-甘氨酸叔丁酯和不同卤代烃的不对称烷基化反应中,所得产物的收率和对映体选择性都较高,而且该催化剂可回收循环使用,说明PTC-1经MWCNTs固载后,仍能够有效地催化多种卤代烃的不对称烷基化反应.

Immobilization of Cinchona Quaternary Ammonium Salts as the Chiral Phase Transfer Catalysts on Multi-walled Carbon Nanotubes and Their Application in Enantioselective Alkylation

The pyrene-tagged cinchona quaternary ammonium salt,the chiral phase transfer catalysts(PTC-1),was synthesized and immobilized on multi-walled carbon nanotubes(MWCNTs).The new catalysts(PTC-1/MWCNTs) were employed in enantioselective alkylation of N-(diphenylmethyene)glycine tert-butyl ester.UV-Vis absorption spectra show the effect of different organic solvents on the adsorption and desorption of PTC-1 onto and from MWCNTs,respectively.The results show that 5.3 mg PTC-1 can be loaded on 10 mg MWCNTs in toluene,and 0.02025 mg PTC-1 was desorbed from 12.7 mg PTC-1/MWCNTs when washed by CHCl3.In the enantioselective alkylation of different halohydrocarbons with N-(diphenylmethyene)glycine tert-butyl ester using PTC-1/MWCNTs as a catalyst,the alkylating products were obtained with high yield and ee value.Furthermore,PTC-1/MWCNTs catalyst can be recovered and used repeatedly.PTC-1/MWCNTs as a new catalyst is effective in enantioselective alkylation of multiple halohydrocarbon.