An Improved Helferich Method for the α/β-Stereoselective Synthesis of 4-Methylumbelliferyl Glycosides for the Detection of Microorganisms
作者:Xianhu Wei、Yanxia Ma、Qingping Wu、Jumei Zhang、Zhihe Cai、Mianfei Lu
DOI:10.3390/molecules201219789
日期:——
An improved Helferich method is presented. It involves the glycosylation of 4-methyl-umbelliferone with glycosyl acetates in the presence of boron trifluoride etherate combined with triethylamine, pyridine, or 4-dimethylaminopyridine under mild conditions, followed by deprotection to give fluorogenic 4-methylumbelliferyl glycoside substrates. Due to the use of base, the glycosylation reaction proceeds more easily, is uncommonly α- or β-stereoselective, and affords the corresponding products in moderate to excellent yields (51%–94%) under appropriate conditions.
提出了一种改进的Helferich方法,涉及在温和条件下,将4-甲基伞形酮与糖基乙酸酯在三氟化硼乙醷存在下与三乙胺、吡啶或4-二甲氨基吡啶联合使用进行糖基化,随后脱保护得到荧光4-甲基伞形酰基糖苷底物。由于使用碱基,糖基化反应更容易进行,具有不寻常的α或β立体选择性,并在适当条件下获得中等至优异的产率(51%至94%)。