Synthesis and NMR spectroscopy of nine stereoisomeric 5,7-diacetamido-3,5,7,9-tetradeoxynon-2-ulosonic acids
作者:Yury E. Tsvetkov、Alexander S. Shashkov、Yuriy A. Knirel、Ulrich Zähringer
DOI:10.1016/s0008-6215(01)00235-x
日期:2001.10
respectively) and their isomers at C-4, C-5, C-7, and C-8 having the L-glycero-D-galacto, D-glycero-D-talo, L-glycero-D-talo, D-glycero-L-altro, L-glycero-L-altro, D-glycero-L-manno, and L-glycero-L-gluco configurations. Synthesis was performed by condensation of 2,4-diacetamido-2,4,6-trideoxy-L-gulose, -D-mannose, -D-talose, and -L-allose with oxalacetic acid under basic conditions, the reaction of the
5,7-二氨基-3,5,7,9-四脱氧非-2-乌磺酸的衍生物是某些细菌多糖和糖蛋白的重要组成部分。为了可靠地建立天然糖的构型,合成了九种立体异构体5,7-二乙酰氨基-3,5,7,9-四脱氧非-2-乌头酸,包括二-N-乙酰基-硫代氨基磺酸和-伪氨基酸( (分别为D-甘油-D-半乳糖和L-甘油-L-甘露糖异构体)及其在C-4,C-5,C-7和C-8处具有L-甘油-D-半乳糖的异构体, D-甘油-D-talo,L-甘油-D-talo,D-甘油-L-altro,L-甘油-L-altro,D-甘油-L-甘露糖和L-甘油-L-葡萄糖构型。在碱性条件下,通过将2,4-二乙酰氨基-2,4,6-三苯氧基-L-古洛糖,-D-甘露糖,-D-塔洛糖和-L-阿洛糖与草乙酸缩合进行合成,最后两种前体的反应伴随着C-2的差向异构。讨论了合成化合物的1H和13C NMR数据。制备了C-7和C-8异构非壬酸的乙酰化甲酯,并用于通过NMR光谱分析侧链构象。