Conversion of Unprotected Aldose Sugars to Polyhydroxyalkyl and <i>C</i>-Glycosyl Furans via Zirconium Catalysis
作者:Nima Ronaghi、David M. Fialho、Christopher W. Jones、Stefan France
DOI:10.1021/acs.joc.0c02176
日期:2020.12.4
An efficient, zirconium-catalyzed conversion of unprotected aldose sugars with acetylacetone to polyhydroxyalkyl furans or C-glycosylfurans is reported. The furan products are formed in up to 93% yield using 5–10 mol % ZrCl4. Pentoses are readily converted at room temperature, while hexoses and their oligosaccharides require mild heating (i.e., 50 °C). Efficient conversions of glycolaldehyde, glyceraldehyde
据报道,未保护的醛糖与乙酰丙酮的有效锆催化转化为聚羟烷基呋喃或C-糖基呋喃。使用5–10 mol%ZrCl 4可以高达93%的产率形成呋喃产物。戊糖在室温下易于转化,而己糖及其寡糖则需要适度加热(即50°C)。还证明了乙醇醛,甘油醛,赤藓糖,庚糖和葡萄糖胺的有效转化。该方法至少在以下方面之一超越了先前的路易斯酸催化方法中的每一种:(i)较低的催化剂负载量;(ii)降低反应温度;(iii)缩短反应时间;(iv)等摩尔底物化学计量;(v)扩大食糖范围;(vi)更高的选择性;(vii)使用富含地球的Zr催化剂。