Chemoselective deacylation of functionalized esters catalyzed by dioxomolybdenum dichloride
摘要:
Among five different oxidometallic species and two Lewis acids investigated, MoO(2)Cl(2) shows the best catalytic and chemoselective activity for the deacylation of esters in methanol at ambient or elevated temperature. Both high efficiency and chemoselectivity were achieved for substrates bearing different ether or ester groups. Acylated mono and disaccharides can also be selectively deacetylated in good yields, leading to useful carbohydrate templates for further synthetic manipulations. (C) 2010 Elsevier Ltd. All rights reserved.
Reinvestigation of <i>N</i>,<i>N</i>-Diacetylimido-Protected 2-Aminothioglycosides in <i>O</i>-Glycosylation: Intermolecular Hydrogen Bonds Contributing to 1,2-Orthoamide Formation
N,N-Diacetylimido protection of 2-aminoglycosides is an elegant strategy but has had limited applications due to unexpected side reactions in glycosylation. We found that high acid concentrations could diminish the side reactions. We observed intermolecular hydrogen bonding among alcohols and acids could disrupt. Assuming that intermolecular hydrogen bonding accelerates the formation of 1,2-orthoamides
To further understand the specificity of muramyl dipeptide (MDP) sensing by NOD2, we evaluated the compatibility of synthetic MDP analogues for cellular uptake and NAGK phosphorylation, the pre-requisite steps of intracellular NOD2 activation.
A highly concise preparation of O-deacetylated arylthioglycosides of N-acetyl-d-glucosamine from 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranosyl chloride and aryl thiols or disulfides
作者:Keith A. Stubbs、Matthew S. Macauley、David J. Vocadlo
DOI:10.1016/j.carres.2005.12.009
日期:2006.7
An expedient and mild route to a range of aryl 2-acetamido-2-deoxy-1-thio-beta-D-glucopyranosides has been devised from 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-alpha-D-glucopyranosyl chloride and arylthiols or aryl disulfides using phase transfer catalysis conditions. This simple procedure compresses up to three synthetic steps into a one-pot reaction, obviating the need for tedious workups and chromatography and directly furnishes crystalline materials in good yields. The procedure is compatible with a range of thiols and disulfides and may be amenable for preparing a wide range of thioglycosides with various glycons and aglycons. (c) 2006 Elsevier Ltd. All rights reserved.
A green and regioselective acetylation of thioglycoside with ethyl acetate
作者:Pi-Hui Liang、Yin-Jen Lu、Ting-Hsuan Tang
DOI:10.1016/j.tetlet.2010.10.135
日期:2010.12
Treatment of saccharidic polyols in ethyl acetate with catalytic sulfuric acid leads to the corresponding primary monoacetate derivatives in good yields. The transesterification was realized by simple stirring without rigorous exclusion of moisture or oxygen. Our protocol is applicable to the regioselective mono-acetylation of amino sugars having different substituents at the 2-positions. (C) 2010 Elsevier Ltd. All rights reserved.