Showing papers on "Aldose published in 1975"

Thio sugars: stereochemical questions and synthesis of antimetabolites

Abstract: Dithioacetals of sugars provide useful starting materials for synthesis of various deoxy sugar derivatives by way of polythio intermediates, and also afford convenient access to acyclic aldose derivatives having two different substituents at C-i. The conformations of aldose diethyl and diphenyl dithioacetals in solution, as determined by p.m.r. spectroscopy with the aid of lanthanide salts, follow the general principle of avoidance of parallel 1,3interactions earlier advanced for peracylated derivatives. The introduction of additional alkylthio groups into the chain, as observed by Brigl, offers a useful route to thio sugars and deoxy sugars, but configurational assignment of the thio derivatives has proved difficult; the extreme readiness whereby 2-alkyl2-thioaldoses undergo epimerization is a contributing factor that has been studied by use of deuterium incorporation and other procedures. The diethyl dithioacetal of 2-S-ethyl-2-thio-D-mannose, a compound whose conformation has been studied comparatively by p.m.r. spectroscopy in solution and by x-ray crystallography in the solid state, is readily converted in high yield into ethyl 2-S-ethyl-2-thio-cx-D-mannofuranoside. The latter compound, also obtainable by nitrous acid deamination of the diethyl dithioacetal of 2-amino2-deoxy-D-glucose, constitutes a convenient starting material for synthesis of 2'-thio and 2'-deoxyfuranosyl nucleosides, certain of which display in vivo tumor-inhibitory activity. Other tumor-inhibitory nucleoside analogues, having an acyclic sugar chain, are obtained from protected aldose dithioacetals by halogenation and subsequent coupling with a derivative of a heterocyclic base, followed by removal of protecting groups. The biological activities of the products show variation according to the stereochemistry of the acyclic chain. These acyclic sugar nucleosides, which have the SR / —CH functionality at C-i, are frequently obtained as pairs of C-i Nbase epimers, and the assignment of stereochemistry at this position is discussed, together with determination of the favored conformation of the acyclic chain.

Novel sugar ureide and thioureide derivatives

Abstract: Novel sugar ureide and thioureide derivatives are provided by this invention, which exhibit certain antibacterial activity against a variety of gram-positive and gram-negative bacteria and useful in therapeutic treatment of bacterial infections. The compounds have the formula ##STR1## wherein R 1 is a monovalent residue of aldose, aldonic acid and their 2-amino derivatives, R 2 is an aralkyl, heterocyclic, sulfamoylaryl, R 3 CONH or R 4 NH-- where R 3 is a heterocyclic and R 4 is an aryl group and Y is oxygen or sulfur atom, which are prepared by reacting an isocyanate or isothiocyanate of the formula R 1 NC=Y with an amino compound of the formula R 2 NH 2 .

Aldose 1,6-diphosphates.

Abstract: Publisher Summary This chapter describes the method for the preparation of aldose 1,6-diphosphates. A microanalytical procedure is developed to measure the effect of time of incubation and temperature on the rate and extent of the phosphorylation reaction. In this assay, the sugar diphosphate product is partially purified and the rate of formation of acid-labile phosphate is measured. The fully acetylated derivative of D-glucose-6-P is prepared by a modification of the procedure used for the synthesis of completely acetylated derivatives of free hexoses with acetic anhydride in pyridine at 3%. Characterization of a-D-glucose 1,6-diphosphate is discussed. The procedure described in the chapter, with slight modifications has been used to prepare α -D-ribose 1,5-diphosphate, α -D-galactose 1,6-diphosphate, α -D-mannose 1,6-diphosphate, and N-acetyl- α -D-glucosamine 1,6-diphosphate. All the sugar diphosphates prepared by this procedure were active when they were assayed for enzymic activity with rabbit muscle phosphoglucomutase. Some precautions must be taken when preparing sugar diphosphates other than α -D-glucose-l,6-P 2 . Several sugar monophosphate samples contain varing amounts of D-glucose-6-P. To remove this impurity, 5-g samples of D-galactose-6-P and D-mannose-6-P were treated with D-glucose- 6-P dehydrogenase and NADP + to convert traces of D-glucose 6-P to 6-P-gluconic acid. One other precaution that must be taken in the preparation of α -D-mannose-l,6-P 2 and α -D-ribose-l,5-P 2 is to reduce the concentration of HC1 from 10 to 5 m M, during the removal of the residual sugar monophosphate. These sugar diphosphates are considerably more labile to acid hydrolysis than α -D-glucose-l,6-P 2 .