A series of C_2-symmetrical chiral 2,5-bis(4'-alkyloxazolin-2-yl) thiophenes(thiobox) have been synthesized from thiophene-2,5-dicarboxylic acid by sequential amidation with achiral ethanolamine, conversion of hyd...A series of C_2-symmetrical chiral 2,5-bis(4'-alkyloxazolin-2-yl) thiophenes(thiobox) have been synthesized from thiophene-2,5-dicarboxylic acid by sequential amidation with achiral ethanolamine, conversion of hydroxyl to chloro group, and base-promoted oxazoline ringformation. As demonstrated by (-)-2,5-bis[4'-(S)-isopropyloxazolin-2'-yl] thiophene, these thioboxsystems exhibited remarkable chirality recognition of 1,1'-bi-2-naphthol giving rise to pronouncedshifts in the ~1H NMR signals of the latter axial chiral compound at the positions of C-3, C-4, C-5,and C-8.展开更多
用1 H NMR和13 C NMR研究了水溶性镧系位移试剂Sm-pdta对反式-4-羟基脯氨酸的手性识别.反式-4-羟基脯氨酸与Sm-pdta形成络合物后,其1 H NMR和13 C NMR图谱的化学位移有所变化,手性碳附近的某些原子所对应的吸收峰裂分为2组信号,分别对...用1 H NMR和13 C NMR研究了水溶性镧系位移试剂Sm-pdta对反式-4-羟基脯氨酸的手性识别.反式-4-羟基脯氨酸与Sm-pdta形成络合物后,其1 H NMR和13 C NMR图谱的化学位移有所变化,手性碳附近的某些原子所对应的吸收峰裂分为2组信号,分别对应反式-4-羟基脯氨酸的两种对映异构体.结果显示,对于反式-4-羟基脯胺酸,Sm-pdta是一个既方便又有效的手性位移试剂.展开更多
文摘A series of C_2-symmetrical chiral 2,5-bis(4'-alkyloxazolin-2-yl) thiophenes(thiobox) have been synthesized from thiophene-2,5-dicarboxylic acid by sequential amidation with achiral ethanolamine, conversion of hydroxyl to chloro group, and base-promoted oxazoline ringformation. As demonstrated by (-)-2,5-bis[4'-(S)-isopropyloxazolin-2'-yl] thiophene, these thioboxsystems exhibited remarkable chirality recognition of 1,1'-bi-2-naphthol giving rise to pronouncedshifts in the ~1H NMR signals of the latter axial chiral compound at the positions of C-3, C-4, C-5,and C-8.
文摘用1 H NMR和13 C NMR研究了水溶性镧系位移试剂Sm-pdta对反式-4-羟基脯氨酸的手性识别.反式-4-羟基脯氨酸与Sm-pdta形成络合物后,其1 H NMR和13 C NMR图谱的化学位移有所变化,手性碳附近的某些原子所对应的吸收峰裂分为2组信号,分别对应反式-4-羟基脯氨酸的两种对映异构体.结果显示,对于反式-4-羟基脯胺酸,Sm-pdta是一个既方便又有效的手性位移试剂.
