A catalytic one-step process for the chemo- and regioselective acylation of Monosaccharides
A catalytic one-step process for the chemo- and regioselective acylation of Monosaccharides
复制标题
DOI：
10.1021/ja074882e
复制
发表时间：
2007-10-24
影响因子：
15
通讯作者：
Schedel, Hartmut
中科院分区：
文献类型：
--
作者：
Kawabata, Takeo;Muramatsu, Wataru;Schedel, Hartmut
发展了一种单糖化学选择性和区域选择性酰化的有机催化方法。在10摩尔%的C-2-对称手性4-吡咯烷基吡啶催化剂（1）的存在下，在-50 ℃下用异丁酸酐处理辛基β-D-吡喃葡萄糖苷，得到作为唯一产物的4-O-异丁酰基衍生物，产率为98%。因此，化学选择性酰化，有利于仲羟基的存在下的游离伯羟基，和区域选择性酰化，有利于三个仲羟基之一，发生了完美的选择性。辛基β-D-吡喃葡萄糖苷与伯醇（2-苯基乙醇）在1存在下用1.1当量异丁酸酐进行竞争性酰化反应，得到辛基β-D-吡喃葡萄糖苷的4-异丁酸酯，区域选择性为99%，产率为98%，这表明碳水化合物的C（4）位仲羟基的酰化反应以加速方式进行。一个可能的机制，涉及1和单糖之间的多个氢键，提出了化学和区域选择性酰化。
An organocatalytic method for the chemo- and regioselective acylation of monosaccharides has been developed. Treatment of octyl beta-D-glucopyranoside with isobutyric anhydride in the presence of 10 mol % of a C-2-symmetric chiral 4-pyrrolidinopyridine catalyst (1) at -50 degrees C gave the 4-O-isobutyryl derivative as the sole product in 98% yield. Thus, chemoselective acylation, favoring a secondary hydroxyl group in the presence of a free primary hydroxyl group, and regioselective acylation, favoring one of three secondary hydroxyl groups, took place with perfect selectivity. A competitive acylation between octyl beta-D-glucopyranoside and a primary alcohol (2-phenylethanol) with 1.1 equiv of isobutyric anhydride in the presence of 1 gave the 4-aisobutyrate of octyl beta-D-glucopyranoside with 99% regioselectivity in 98% yield, which indicates that acylation of the secondary hydroxyl group at C(4) of the carbohydrate proceeds in an accelerative manner. A possible mechanism, involving multiple hydrogen-bonding between 1 and the monosaccharide, is proposed for the chemo- and regioselective acylation.