Institution:国家糖工程技术研究中心
Journal:ACS Catalysis
Place of Publication:American Chemical Society
Key Words:chiral catalyst, bifunctional thiourea catalysis, regioselective acylation, carbohydrates, vicinal trans-diols
Summary:Regioselective protection of the polyfunctionalcarbohydrates with acyl groups under catalytic conditions is aprerequisite for efficient structural modification and chain extension via glycosidation. A general and also strong “axial oxy group effect”was now observed with benzoyl cyanide as the acylating agent and
4-dimethylaminopyridine as the catalyst, permitting the preferred
O-acylation of equatorial hydroxy groups next to axial oxy groups. This effect is substantiated with 2,3-O-unprotected β-D-galacto- and α-D-glucopyranosides and 3,4-O-unprotected mannopyranosides possessing vicinal trans-diol moieties. Moreover, vicinal trans-diols with axial oxy groups next to each hydroxy group, possessing expectedly comparable reactivity, could be differentiated with chiral tertiary amine catalysts. Particularly interesting in this regard is the action of bifunctional (S,S)-N-(N,N-dialkylaminocyclohexyl)-thioureas as catalysts; they favor 2-O-benzoylation of 2,3-O-unprotected α-galactopyranosides, as is also supported by density functional theory calculations. This directing effect can be reversed with quinidine as the catalyst or with bulky substituents at the
anomeric position.
First Author:李天路,李彤,Michael Linseis
Correspondence Author:Richard R. Schmidt,彭鹏
All the Authors:王凤山,Rainer F. Winter
Indexed by:Journal paper
Volume:10
Issue:19
Page Number:11406
Translation or Not:No
Date of Publication:2020-09
Included Journals:SCI