Tosylation of non-protected glycopyranosides with p-toluenesulfonyl chloride in the presence of 4-dimethyl-aminopyridine, after activiation of the glycosides by dibutyltin oxide, gave mono-O-tosylates in good yield. The regioselectivity in this tosylation was different from that in the corresponding benzoylation for some glycosides. The reason for this difference is discussed based on an equilibrium of the tin intermediates and kinetic attack of the tosyl chloride on the intermediates. Thus, by application of this tosylation method to non-protected and partially protected glycosides, various glycoside mono-O-tosylates were synthesized regioselectively.
在二
丁基锡氧化物活化糖苷后,使用
对甲苯磺酰氯和4-二甲
氨基吡啶的存在下,对非保护性糖苷进行
甲苯磺酰化反应,可得到产量良好的单-O-
甲苯磺酸酯。某些糖苷在这种
甲苯磺酰化反应中的区域选择性与相应的苯甲酰化反应不同。这种差异的原因基于
锡中间体的平衡和甲
苯磺酰氯对中间体的动力学攻击。因此,通过将这种方法应用于非保护性和部分保护性糖苷,可以区域选择性地合成各种糖苷单-O-
甲苯磺酸酯。