Glycan ester deacylation by TBAOH or TBAF: regioselectivity vs. polysaccharide structure
Ruoran Zhang1, Xueyan Zheng2, Joyce Kuang3
1Macromolecules and Interfaces Institute, Virginia Tech, Blacksburg, VA 24061, United States.
Carbohydrate Polymers
|September 27, 2014
Summary
Tetrabutylammonium fluoride (TBAF) and tetrabutylammonium hydroxide (TBAOH) enable regioselective deacylation of cellulose esters, targeting hindered positions. This reaction
Area of Science:
- Carbohydrate Chemistry
- Organic Synthesis
- Polymer Science
Background:
- Cellulose esters are important biomaterials.
- Regioselective modification of polysaccharides is challenging.
- Tetrabutylammonium fluoride (TBAF) and tetrabutylammonium hydroxide (TBAOH) are basic reagents.
Purpose of the Study:
- To investigate the generality of TBAF/TBAOH mediated deacylation on various glycan esters.
- To examine the impact of glycan structure on deacylation regioselectivity.
- To explore regioselective removal of acyl groups from polysaccharides.
Main Methods:
- Deacylation of cellulose, amylose, curdlan, dextran, pullulan, and glucomannan esters.
- Treatment with tetrabutylammonium fluoride (TBAF) or tetrabutylammonium hydroxide (TBAOH).
- Analysis of deacylation products to determine regioselectivity.
Main Results:
- TBAF/TBAOH mediated regioselective O-2/3 deacylation of cellulose esters.
- Remarkably regioselective O-2/3 deacylation of amylose triesters.
- Moderately regioselective O-2/4 deacylation of curdlan triester.
- No regioselectivity observed for dextran triester due to its structure.
- Deacylation observed for pullulan and glucomannan triesters, but regioselectivity is undetermined due to product complexity.
Conclusions:
- TBAF/TBAOH deacylation is a versatile method for modifying glycan esters.
- The regioselectivity of deacylation is influenced by the glycan's structural features.
- Further investigation is needed for complex glycans like pullulan and glucomannan.
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