Quantifying the Electronic Effects of Carbohydrate Hydroxy Groups by Using Aminosugar Models
作者:Christian M. Pedersen、Jacob Olsen、Azra B. Brka、Mikael Bols
DOI:10.1002/chem.201100020
日期:2011.6.14
their pKa values determined by titration. These model compounds were chosen because they are the amino derivatives of the most common glycosyl acceptors. From this study it was possible to evaluate the electron density at each of the given positions in the carbohydrate and compare them. Some general trends were observed: The basicity of the amino groups decreases in the order 6‐NH2>3‐NH2>2‐NH2>4‐NH2
合成了具有α-和β-葡萄糖,α-半乳糖或α-甘露糖立体化学的甲基氨基脱氧糖苷,在四个可能的非异头位置中均具有氨基官能团,并通过滴定确定了其p K a值。选择这些模型化合物是因为它们是最常见的糖基受体的氨基衍生物。通过这项研究,有可能评估碳水化合物中每个给定位置的电子密度并进行比较。观察到一些一般趋势:氨基的碱度以6-NH 2 > 3-NH 2 > 2-NH 2 > 4-NH 2的顺序降低。(指的是位置)。当糖环上的一个或多个取代基为轴向时,氨基脱氧糖α的碱性通常会增加。当胺对氧原子为反平面时,碱度降低。这些发现与从糖基化化学和糖的区域选择性保护获得的观察结果一致。