Zbigniew J. Witczak

Monosaccharide isothiocyanates and thiocyanates: synthesis, chemistry, and preparative applications

Publisher Summary This chapter presents the synthesis, chemistry, and preparative applications of monosaccharide isothiocyanates and thiocyanates. The ability of the isothiocyanate group to participate in nucleophilic reaction provides an attractive approach to nucleoside analogs and other nitrogen and sulfur heterocycles. Sugar thiocyanates are generally good precursors for the synthesis of thio and deoxy sugars and they are readily synthesized by a variety of methods from the corresponding halides. The thermodynamically more-stable isothiocyanate may also be formed by a secondary, isomerization reaction. It is found that that the treatment of semicarbazide with a nitroso acid at 0° affords the 1,2,3,4-thiatriazole derivative by addition and cyclization. The same 1,2,3,4-thiatriazole derivative 39 was obtained by the treatment of isothiocyanate 2 with hydrazoic acid. It is observed that isothiocyanate reacts with glycine, as well as with β-alanine, in tetrahydrofuran (THF) solution with the formation of corresponding N -(carboxyalky1)- d -gluconamides by nucleophilic attack of the amino group on the hard site, with simultaneous elimination of a molecule of thiocyanogen. The ability of aryl and alkyl isothiocyanates to react with reducing agents such as triethyl phosphite, triethylphosphine, or triphenyltin hydride to form the corresponding isocyanide is also elaborated in the chapter.

An approach to a new class of selenosugars : A convenient synthesis of glycosyl isoselenocyanates

Abstract A new class of selenosugars—glycosyl isoselenocyanates—has been prepared via reaction of the corresponding glycosyl isocyanides with elemental Se under the catalytic influence of triethylamine. 2,3,4,5,6-Penta-O-acetyl-D-gluconyl isoselenocyanate was also prepared in moderate yield by reaction of 2,3,4,5,6-penta-O-acetyl-D-gluconyl chloride with potassium selenocyanate in anhydrous acetone. The isoselenocyanate structure is ascertained by physical (13C-NMR, IR) and chemical methods—formation of selenoureas, and radical induced fragmentation by reaction with tri-n-butyltin hydride via intermediate isocyanide, to 1,5-anhydro-D-hexitols.

Synthesis of 3-C-(hydroxymethyl)erythritol and 3-C-methylerythritol

3-C-(Hydroxymethyl)erythritol was prepared from 3-C-(hydroxymethyl)-2,3-O-isopropylidene-D-erythro-tetrofuranose (4) by hydrolysis followed by reduction, or by reduction followed by hydrolysis. Monotosylation of 4, followed by reduction with lithium aluminum hydride and hydrolysis, afforded 3-C-methylerythritol.

Review Article Monosaccharide Isocyanides, Synthesis, Chemistry and Application

Abstract Attention has been recently directed toward synthesis of various types of heterocyclic derivatives, among them nucleoside analogs with potential antibacterial and antitumor properties.1 Although a number of synthetic approaches have been developed, there are a few methods that appear to have the versatility for construction of a variety of heterocyclic systems. Among these are approaches that employ heterocyclic elaboration of glycosyl cyanides,2 important -glycosyl intermediates that have been used in the synthesis of a number of naturally occurring -nucleoside antibiotics3 as well as many analogs.2,4

Monosaccharides with Phosphorus in the Sugar Ring

Abstract In recent years attention has been directed toward the synthesis of modified sugars wherein the oxygen atom in the sugar ring is replaced by sulfur, selenium or phosphorus. Synthesis of sugar analogs with phosphorus as the ring heteroatom is interesting from the point of view of their possible biological activity.

Synthesis of some derivatives of 6-amino-1,5-anhydro-6-deoxy-D-glucitol and 2-amino-1,5-anhydro-2-deoxy-D-glucitol.

6-Amino-1,5-anhydro-6-deoxy-D-glucitol (11) was prepared from 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl bromide (1) in six steps. Reduction of 1 with tributyltin hydride, followed by deacetylation, monomolar tosylation, and reacetylation, afforded 2,3,4-tri-O-acetyl-1,5-anhydro-6-O-toluene-p-sulfonyl-D-glucitol (9). Alternatively, tritylation of 1,5-anhydro-D-glucitol, followed by acetylation, detritylation, and tosylation, gave 9. Mesylation gave 8. Treatment of 8 or 9 with azide anion afforded the azide 10, reduction of which with tributyltin hydride gave 11, which was mesylated or tosylated, and then deacetylated to give the 6-methane-sulfonamido or 6-toluene-p-sulfonamido derivative. Similarly, mesylation or tosylation of 3,4,6-tri-O-acetyl-2-amino-1,5-anhydro-2-deoxy-D-glucitol (20) gave the 2-methanesulfonamido or 2-toluene-p-sulfonamido derivatives. Treatment of 11 and 20 with sulfur trioxide-pyridine afforded the sulfoamino derivatives, deacetylation of which gave sugar analogs of cyclamate-like compounds.