Novel 3-O-propargyl cellulose as a precursor for regioselective functionalization of cellulose

For the first time, the synthesis of 3-O-propargyl cellulose could be realized using the thexyldimethylsilyl moiety as protecting group. The treatment of 3-O-propargyl-2,6-di-O-thexyldimethylsilyl cellulose with tetrabutylammonium fluoride trihydrate leads to the complete removal of the silicon containing groups. The structure and the high regioselectivity were confirmed by NMR spectroscopy. Preliminary studies have shown that a subsequent cycloaddition reaction of the triple bond of the propargyl group with azido-propyl-polyamidoamine (PAMAM) dendrons (some type of click-chemistry) yields dendritic structures based on cellulose. Characterization was carried out by 1D and 2D NMR spectroscopy that gives evidence for the unconventional structure.