Improved Synthesis of 2-Deoxy-2-fluoro-D-glucose Using Fluoride Ion

Methyl 3-O-benzyl-4,6-O-benzylidene-2-O-(trifluoromethanesulfonyl)-β-D-mannopyranoside (7) was examined as a substrate for the preparation of 2-deoxy-2-fluoro-D-glucose (1) by fluoride ion treatment. The triflate (7) reacted rapidly with tetraalkylammonium fluorides in acetonitrile or tetrahydrofuran to give methyl 3-O-benzyl-4,6-O-benzylidene-2-deoxy-2-fluoro-β-D-glucopyranoside (10) in 52-57% yield. Removal of the protecting groups from 10 by the use of 50% methanesulfonic acid afforded the required 1 in good yield. This synthetic sequence may provide an effective alternative to known methods for preparing ^<18>F-labeled 1.