Abstract
Nucleophilic displacement reactions of the 3-O-methyl, and 3-O-benzyl derivatives (5, 11, and 12) of methyl 4, 6-O-benzylidene-2-O-(trifluoromethanesulfonyl)-β-D-glucopyranoside with tetraalkylammonium fluorides in acetonitrile proceeded smoothly to give, with inversion of configuration at C2, the corresponding methyl 2-deoxy-2-fluoro-β-D-mannopyranosides in good yields. Similar treatment of methyl 3-O-benzyl-4, 6-O-benzylidene-2-O-(trifluoromethanesulfonyl)-α-D-glucopyranoside (3) or methyl 3, 4, 6-tri-O-acetyl-2-O-(trifluoromethanesulfonyl)-β-D-glucopyranoside (8) resulted in decreased yield of the fluoro-manno compound. Efficient conversion of these fluorinated intermediates into 2-deoxy-2-fluoro-D-mannose (1) was achieved by heating with acidic reagents. These synthetic sequences could be easily adapted for the preparation of the 18F-labeled analog of 2-deoxy-2-fluoro-D-mannose (1).
