Functional Group Tolerance in Organocatalytic Regioselective Acylation of Carbohydrates
摘要:
Organocatalytic regioselective acylation of mono- and disaccaharides with various functionalized acid anhydrides has been developed. Acylation Of octyl beta-D-glucopyranoside with acid anhydrides derived from alpha-amino acids, cinnamic acid, and gallic acid took place at C(4)-OH with 67-94% regioselectivity in the presence of catalyst 1. Regioselective acylation of disaccharides with functionalized acid anhydrides was also achieved with 78-94% selectivity. Especially, a disaccharide with seven free hydroxy groups (X = OH, R' = H) underwent acylation at C(4)-OH with 78% regioselectivity in the presence of 1. Thus, functional group tolerance in the regioselective acylation catalyzed by I was found to be high.
Amine-free silylation of various alcohols catalyzed by 4-methylpyridine N-oxide in the presence of MS4A at room temperature was developed. This simple method gave various silyl ethers in a high yield. (C) 2015 Elsevier Ltd. All rights reserved.
Regioselective acylation of 6-O-protected octyl β-d-glucopyranosides by DMAP catalysis
作者:Wataru Muramatsu、Takeo Kawabata
DOI:10.1016/j.tetlet.2007.05.098
日期:2007.7
Regioselectivity of acylation of 6-O-protected octyl P-D-glucopyranosides was investigated. Treatment of octyl 6-O-methyl-beta-D-glucopyranoside with isobutyric anhydride in the presence of DMAP in toluene at -40 degrees C gave 3-0-isobutyryl derivative in >99% regioselectivity. Similar treatment of octyl 6-O-TBS-beta-D-glucopyranoside at -20 degrees C also gave 3-0-isobutyryl derivative in >99% regioselectivity. (C) 2007 Elsevier Ltd. All rights reserved.