Fluorination of carbohydrates

With certain exceptions, primary fluorination of carbohydrate derivatives is very facile. Fluoride displacement of sulfonyloxy groups by potassium, or cesium, fluoride in 1,2-ethanediol and a variety of other solvents has frequently been used. Tetrabutylammonium (sometimes tetraethylammonium) fluoride in dipolar, aprotic solvents (mainly ace-... 

Also unsuccessful have been all attempts to decarboxylate fluoroformates of various carbohydrates, but it has been shown that an excess of reagent, solvent, temperature and time of reaction are all of great importance in obtaining high yields for the fluorination of carbohydrate chloroformates (Table l).5... 

Fluorination of trifluoromethanesulfonyl carbohydrates with cesium fluoride under forcing conditions (130 °C in dimethylformamide) [55] or the use of acetyl protected substrates [56] gives considerably lower yields... 

Research that Stacey was particularly associated with in the earlier years, which bridged fluorine and carbohydrate chemistry, included studies of trifluo-roacetic acid and its anhydride. These were among the first organic fluorides to... 

An alternative procedure for the introduction of the fluorine substituent in secondary positions of carbohydrates consists in nucleophilic displacement of sulfonic esters. Walden inversion always accompanies such displacements, and the success of this method may be attributed to two factors. 

The influence of substituents on the regioselectivity of fluorination of allylic alcohols with DAST has been studied and halogenation of the nitrogen of carbohydrate A-acetyl side-chains by HOCl has been monitored. ... 

The next chapter, by Ren Csuk and Brigitte I. Glanzer (Zdrich), constitutes an extensive treatise on the nuclear magnetic resonance (n.m.r.) spectroscopy of fluorinated monosaccharides [whose early chemistry was surveyed in Vol. 38 (1981) by Anna A. E. Penglis] the comprehensive data tabulated herein should be especially of value to those working in the fleld. It continues the coverage, in Advances, of n.m.r. spectroscopy as the key tool for characterization of carbohydrates. It complements articles on the H-n.m.r. spectroscopy of carbohydrates by Laurance D. Hall [Vols. 19 (1964) and 29 (1974)], Bruce Coxon [Vol. 27 (1972)], and Johannes F. G. Vliegenthart, Lambertus Dorland, and Herman van Halbeek [Vol. 41 (1983)], and on the C-n.m.r. spectroscopy of monosaccharides by Klaus Bock and Christian Pedersen [Vol. 41... 

The selective introduction of fluorine is of continuing interest not only because of the synthetic challenge but also because of the possibility of a dramatic change in biological activity. The fluoride-ion displacement of carbohydrate trifluoromethanesulfonates using tris(dimethylamino)sulfonium... 

Not surprisingly, one of the most common reactions of pyrrolo[2,3- ]pyrimidines is nucleoside formation. Typical of the process is the reaction of 5 with the fluorine-containing carbohydrate moiety 6 to produce the nucleoside 7 (Scheme 1) <1995JME3957>. Numerous other reports are described in the literature but the number is too large to be cited here. 

Table 3. Fluorination of Hydroxy Groups in Carbohydrates, Nucleosides, Steroids, and Natural Products Using (Dialkylamino)trifluoro-/. -sulfanes...

The same sequence of diastereoselective reduction of a /i-oxo-y-fluoro sulfoxide followed by Pummerer rearrangement and hydrolysis to the aldehyde has been used successfully in the synthesis of fluorine-containing carbohydrates.10... 

Organofluorine Compounds and Fluorinating Agents. Part 17. Sonochemical-Forced Preparation of Perfluoroalkanals and Their Use for Non-Conventional Acetalations of Carbohydrates ... 

Glycosylfluorides. Two laboratories1,2 have reported that the free anomeric hydroxyl group of carbohydrates is replaced by fluorine on treatment with DAST. 

The survey is intended to cover the published literature on the subject as fully as possible. Although the four halogens are well known as constituents of a wide range of carbohydrate compounds, radical-mediated halogenations have, in most cases, been realized only with bromine. There are, however, some examples of chlorinations to the best of our knowledge, there are no reported fluorinations or iodinations which occur by direct, radical-mediated processes. The radical-mediated reactions by which bromodeoxy carbohydrates are obtainable from benzylidene acetals17-19 are not considered. 

D. J. Baillargeon and G. S. Reddy, Novel 2,6-anhydro-/l-D-hexopyranosyl fluorides by fluorination of l,6-anhydro-/j-D-hexopyranoses with diethylaminosulfur trifluoride, Carbohydr. Res., 154 (1986) 275-279. 

Floridose, IV, 275 Fluorine, as oxidant, III, 133 Fluorine derivatives of carbohydrates, III, 100... 

The introduction of fluorine in the secondary position of carbohydrates, i.e. in the sugar ring skeleton, with potassium fluoride is even more difilcult. However, a 4-mesyloxy group in a gluco configuration, where H5 and H3 are not /ranj-diaxial, can be substituted with potassium fluoride in good yield.Finally, it should be mentioned that F has been introduced in the carbohydrate skeleton by the use of CsHi FJF. ... 

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