Regioselective methylation of methyl glycopyranosides with diazomethane in the presence of transition-metal chlorides and of boric acid
作者:Evgeny V. Evtushenko
DOI:10.1016/s0008-6215(99)00044-0
日期:1999.3
Abstract Partial methylation of the methyl pyranosides of a number of pentoses, hexoses, 6-deoxyhexoses, methyl uronates and their methyl ethers with diazomethane in the presence of transition-metal chlorides and boric acid was studied. It was found for methyl glycosides of pentoses and 6-deoxyhexoses that tin(II), antimony(III), and titanium(IV) chlorides as well as boric acid promoted substitution
摘要研究了在过渡金属氯化物和硼酸存在下,许多戊糖,己糖,6-脱氧己糖,尿酸甲酯及其甲基醚的甲基吡喃糖苷与重氮甲烷的部分甲基化。发现戊糖和6-脱氧己糖的甲基糖苷中锡(II),锑(III)和钛(IV)氯化物以及硼酸主要促进OH-3的取代,但被铈(III)和锌的取代(II)观察到盐主要取代了OH-2。在所有情况下,甲基β-1-鼠李糖吡喃糖苷的甲基化表现出较高的OH-2反应性。在氯化锡(II),锑(III)和铈(III)的存在下,己糖甲基糖苷的甲基化反应主要产生了3-甲基醚。不参与进一步络合的3-甲基醚 积聚高达50-80%的反应混合物(95%至100%的单甲醚馏分)。建议用于许多糖的方便的甲基醚的合成。