呋喃阿洛糖衍生物水解产物的结构确定

摘要

1,2;5,6-双-O-异丙叉基-3-C-硝甲基-α-D-呋喃阿洛糖(化合物1)在酸性条件下选择性脱除5,6-异丙叉基得到C-3位构型保持的水解产物1,2-O-异丙叉基-3-C-硝甲基-α-D-呋喃阿洛糖(化合物2);化合物1先经过Moffatt脱水生成C-3硝基烯产物1,2;5,6-双-O-异丙叉基-3-脱氧-亚甲基硝基-α-D-呋喃木糖(化合物3),然后在酸性条件下选择性脱除5,6-异丙叉基过程中协同发生氧杂-Michael加成反应得到C-3位构型反转的水解产物1,2-O-异丙叉基-3-C-硝甲基-α-D-呋喃葡萄糖(化合物2′),两种产物化合物2和2′互为C-3差向异构体.通过1H NMR、13C NMR、DEPT-135、1H-1H COSY、gHSQC和gHMBC等核磁共振(NMR)技术,对化合物2′的1H和13CNMR数据进行了全归属.%1,2-O-(1-methylethylidene)-3-C-methylnitro-α-D-allofuranose(2)was obtained through selective deprotection of1,2;5,6-Di-O-isproplidene-3-C-methylnitro-α-D-allofuranose(1)underanacidic condition. C-3 nitrostyrenes(3)was synthetizedthrough Moffatt dehydration from compound1underanacidic condition.A hydrolysis product 1,2-O-(1-methylethylidene)-3-C-methylnitro-α-D-glocufuranose(2')which hada reversedC-3 configuration wasobtained by an unexpected oxa Michael addition.Compounds2and2'were C-3 diasteroisomers.Compound2'was characterized withNMR spectroscopy techniques, including1HNMR,13CNMR,DEPT-135,1H-1H COSY, gHSQC and gHMBC.1H and 13Cchemical shiftsof compound2'were also fullyassigned. The molecular structure of compound2'was determined.