Glycosidation–Anomerisation Reactions of 6,1-Anhydroglucopyranuronic Acid and Anomerisation of β-D-Glucopyranosiduronic Acids Promoted by SnCl4
作者:Colin O'Brien、Monika Poláková、Nigel Pitt、Manuela Tosin、Paul V. Murphy
DOI:10.1002/chem.200601111
日期:2007.1.12
onic acids was found to be faster, in some cases, than anomerisation of related beta-D-glucopyranosiduronic acid esters and beta-D-glucopyranoside derivatives and the rates are dependent on the structure of the aglycon. Moreover, the rates of anomerisation of beta-D-glucopyranuronic acid derivatives can be qualitatively correlated with rates of hydrolysis of beta-D-glucopyranosiduronic acids. Mechanistic
氯化锡(IV)催化的甲硅烷基化亲核试剂与6,1-脱水葡萄糖基吡喃糖醛酸(葡萄糖醛酸6,1-内酯)的反应提供了1,2-反式或1,2-顺式(脱氧)糖苷,具体取决于供体结构。对于供体与2-酰基和2-脱氧供体的反应,获得了α-糖苷,而2-脱氧-2-碘的供体给出了β-糖苷。实验证据表明,当1,2-顺式糖苷形成时,由SnCl(4)催化的最初形成的1,2-反式糖苷的异构化是可能的。在某些情况下,发现β-D-吡喃葡萄糖苷神经酸酯的异构化比相关的β-D-吡喃葡萄糖苷神经酸酯和β-D-吡喃葡萄糖苷衍生物的异构化更快,并且速率取决于糖苷配基的结构。而且,β-D-吡喃葡萄糖醛酸衍生物的异构化速率可以与β-D-吡喃葡萄糖醛糖醛酸的水解速率定性相关。考虑了反应的机械可能性。