Efficient Syntheses of β-Cyanosugars Using Glycosyl Iodides Derived from Per-O-silylated Mono- and Disaccharides
摘要:
[GRAPHICS]Reported herein is a general method for the efficient syntheses of a variety of beta -cyano glycosides through the activation of per-O-trimethylsllyl glycosides with TMSI to form alpha -glycosyl iodides, which undergo S(N)2-type displacement when treated with tetrabutylammonium cyanide. The cyanoglycosides were reduced under mild conditions using NaBH4 in the presence of catalytic CoCl2(H2O)(6) in THF/H2O to give the corresponding aminomethyl glycosides.
Selective Acetylation of Non-anomeric Groups of per-<i>O</i>-Trimethylsilylated Sugars
作者:Welday Desta Weldu、Cheng-Chung Wang
DOI:10.1021/acs.joc.0c02813
日期:2021.4.2
Selective modification of the hydroxyl groups of sugars has been a long-standing challenge due to their proximate relative reactivity. Herein, we report a TMSOTf-catalyzed selective acetylation of the non-anomeric hydroxyl groups of several per-O-TMS-protected sugar substrates while leaving their anomeric group unaffected. In addition to standing versatile by itself, the anomeric O-TMS group left intact
Novel eco-friendly solution for the regioselective acetylation of per-O-TMS carbohydrates
作者:Lina Jin、Xianya Mao、Zhikun Wang、Yangyi Mao、Jianwei Mao、Yanli Cui
DOI:10.1016/j.carres.2020.108074
日期:2020.9
Regioselective acetylation of per-O-TMS carbohydrates was achieved preferentially at the 6 position or 1,6-position under mild conditions involving the eco-friendly solvent acetonitrile, at room temperature, in ambient atmosphere and in a shorter time. Good or moderate yields were obtained via 4-dimethylaminopyridine, without auxiliary equipment. A single α-O-Acetyl acetylation anomer was exclusively
A convenient methodology has been developed for the regioselective removal of primary trimethylsilyl group (TMS) of various per-O-TMS-protected carbohydrates by inexpensive ammonium acetate. After acetylation and trichloroacetimidation of 6-hydroxyl sugar 1b, other TMS groups of 1d and 1c were inert to ammonium acetate in the same conditions, and this approach was also successfully applied in TMS-protected sphingosine. (C) 2013 Elsevier Ltd. All rights reserved.