NEW APPROACHES TO SYNTHESIS OF 3-DEOXY-3-FLUORO-D-GLUCOSE

The diisopropylidene hexose derivatives l, 2:5, 6-di-O-isopropylidene-α-D-glucofuranose (1) and l, 2:5, 6-di-O-iso-propylidene-α-D-allofuranose (4) react with diethylaminosulfur trifluoride (DAST) to give stable but labile intermediates which can undergo further nucleophilic attack at sulfur rather than fluorination. Distillation of the reaction mixtures of 1 and DAST gives 3-deoxy-l, 2:5, 6-di-O-isopropylidene-α-D-glaco-hex-3-enofuranose (3), while 5 and DAST gave 3-deoxy-3-fluoro-l, 2:5, 6-di-O-isopropylidene-α-D-glucofuranose (6). The formation of 6 is shown to be an SN2 displacement by labeling experiments with the radioisotope 18F. In a rapid and simple reaction, 6 can also be prepared from the trifluoromethanesulfonate of 5 and cesium fluoride. © 1978, American Chemical Society. All rights reserved.