Collect. Czech. Chem. Commun. 2001, 66, 1665-1681

Alkylation of Partially Protected Xylofuranoses and Tetritols with (2,2,3,3,4,4,5,5,6,6,7,7,7-Tridecafluoroheptyl)oxirane and the Stability of Protecting Acetal Groups Towards Lewis Acid-Type Catalyst

Karel Kefurta,*, Jitka Moravcováa, Šárka Bambasováa, Kateřina Buchalováa, Barbora Vymětalíkováa, Zdeňka Kefurtováa, Jan Staněka and Oldřich Paletab

a Department of Chemistry of Natural Compounds, Institute of Chemical Technology, Prague, 166 28 Prague 6, Czech Republic
b Department of Organic Chemistry, Institute of Chemical Technology, Prague, 166 28 Prague 6, Czech Republic


1,2-O-Isopropylidene-3-O-methyl-α-D-xylofuranose (2), 1,2-O-isopropylidene-α-D-xylofuranose (3), 2,4-O-ethylidene-D-erythritol (4) and 1,3-O-ethylidene-D-threitol (5) were alkylated with racemic (2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptyl)oxirane (1) using boron trifluoride diethyl etherate as a catalyst. The desired mono- or disubstituted polyfluoroalkyl derivatives 6-11 were isolated only in low to medium yields. The fluoroalkylation was accompanied with disproportional distributions of the protecting acetal/ketal groups and polymerization of saccharides. Therefore the stability of 3, 4, 5, 5-O-acetyl-1,2-O-isopropylidene-α-D-xylofuranose (14) and 1,2-O-isopropylidene-α-D-glucofuranose (15) in the presence of a catalytic amount of boron trifluoride diethyl etherate was investigated in various solvents. A mechanism explaining the effect of the catalyst has been proposed.

Keywords: Carbohydrates; Fluoroalkylated epoxides; Ring opening; Lewis acid catalysis; Fluoroalkylations; Fluorophilic sugars; Oxygen carriers; Fluorinated sugars.

References: 39 live references.