Deoxyfluoroketohexoses: 4-deoxy-4-fluoro-D-sorbose and -tagatose and 5-deoxy-5-fluoro-L-sorbose

4-Deoxy-4-fluoro-α-D-sorbose (6) was prepared in crystalline form by the action of potassium hydrogen fluoride on 3,4-anhydro-1,2-O-isopropylidene-β-D-psicopyranose (3) followed by deacetonation. Under identical conditions 3,4-anhydro-1,2-O-isopropylidene-β-D-tagatopyranose (7) underwent epoxide migration to give 4,5-anhydro- 1,2-O-isopropylidene-β-D-fructopyranose (12), which after deacetonation yielded 4-deoxy-4-fluoro-D-tagatose (15) 5-deoxy-5-fluoro-α-L-sorbopyranose (16) the latter as the crystalline free sugar. The action of glycol-cleavage reagents on the isopropylidene acetals of the deoxyfluoro sugars was consistent with the assigned structures. The structures were established by ¹³C n.m.r. studies of the free deoxyfluoro sugars 6 and 16 of the isopropylidene acetal 13, and by ¹H n.m.r. studies on the acetylated isopropylidene acetals 5 diacetate, 13 diacetate, and 14 diacetate. 5-Deoxy-5-fluoro-L-sorbose (16) was biologically active producing in mice effects characteristic of deoxyfluorotrioses and of fluoroacetate. 4-Deoxy-4-fluoro-D-tagatose (15) and 4-deoxy-4-fluoro-D-sorbose (6) produced no apparent effects in mice up to a dose of 500 mg/kg. The implications of these findings with respect to transport phosphorylation, and the action of aldolase on ketohexoses are discussed.