Temperature Dependence of the Distribution of Trityl Groups in the Tritylation of 1,2-O-Isopropylidene-.ALPHA.-D-glucofuranose.
作者:Naohiko MORISHIMA、Yoko MORI
DOI:10.1248/cpb.47.1481
日期:——
The tritylation reaction of 1, 2-O-isopropylidene-α-D-glucofuranose with 2.4 molar amounts of trityl chloride in pyridine at 70°C for 20 h gave the 5, 6-di-O-trityl derivative in 50% yield as the major product, whereas the reaction at 115°C mainly gave the 3, 6-di-O-trityl derivative (26% yield) along with the 6-O-trityl derivative (48% yield). The fact that the yield of the 5, 6-di-O-trityl derivative at 115°C decreased after 1 h and was 12% at 20 h is due to the redistribution of trityl groups including detritylation assisted by pyridinium chloride. It was found that tritylation of the primary hydroxyl group at C-6 was almost completed within 10 min at 115°C.
1, 2-O-异亚丙基-α-D-呋喃葡萄糖与 2.4 摩尔量的三苯甲基氯在吡啶中的三苯甲基化反应在 70°C 进行 20 小时后,主要产物为 5, 6-二-O-三苯甲基衍生物,产率为 50%;而在 115°C 进行反应时,主要产物为 3, 6-二-O-三苯甲基衍生物(产率为 26%)和 6-O-三苯甲基衍生物(产率为 48%)。在 115°C 下,5, 6-二-O-三苯甲基衍生物的产率在 1 小时后下降,在 20 小时后降至 12%,这是由于三苯甲基基团的重新分布,包括在氯化吡啶的辅助下发生的脱三苯甲基作用。研究发现,在 115°C 下 10 分钟内,C-6 处的主羟基的三苯甲基化几乎完成。