Synthesis of 2-S-dioxo isosteres of purine and pyrimidine nucleosides. II

The preparation of glucosyl and ribosyl derivatives of 3,4,5-triamino-2H-1,2,6-thiadiazine 1,1-dioxide ( 2 ), 7-amino-4H-furazano[3,4-c]- and 7-amino-1H, 4H-imidazo[2,3-c][1,2,6]thiadiazine 5,5-dioxide ( 3 and 4 respectively) is described. Different synthetic approaches have been used.     

核苷研究2: 苄基糖核苷的立体选择性合成

1-(2, 3, 4, 6-O-四苄基吡喃糖基)-三氟乙酸酯或三氯乙酸酯在无水四氯化锡存在下与一些具有代表性的硅醚保护的碱基或者含氮杂环化合物反应, 合成了一系列新的苄基糖苷。对三氟乙酰氧基、三氯乙酰氧基作为新的离去基在核苷合成中的反应活性、立体选择性和反应收率进行了讨论。     

Acyclic analogs of nucleosides. Synthesis of hydroxyalkyl derivatives of 2-trifluoromethyl- and 2-trifluoromethylthiobenzimidazole

1-(2,3-Dihydroxypropyl)-, 1-(4-hydroxy-2-oxabutyl)-, 1-(3-hydroxymethyl-4-hydroxy-2-oxabutyl)-, 1-(1,5-dihydroxy-3-oxa-2-pentyl)-, 1-(5-hydroxy-3-oxa-2-pentyl)-, and 1-(4,5-dihydroxy-2-oxapentyl)-2-trifluoromethyl- and -2-trifluoromethylthiobenzimidazoles were obtained by condensation of trimethylsilyl derivatives of 2-substituted benzimidazoles with alkylating agents in the presence of SnCl₄, or by direct alkylation of the sodium salts of the heterocycles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 632–636, May, 1988.     

Alkylating nucleosides. 3. The reaction of 3,5-dimethylpyrazole nucleosides with N-bromosuccinimide

Bromination of 3,5-dimethylpyrazole nucleosides with N-bromosuccinimide gave the corresponding 4-bromo-3,5-dimethylpyrazole, 3-methyl-5-(bromomethyl)pyrazole and 4-bromo-3-methyl-5-(bromomethyl)pyrazole nucleosides. Structural assignments were made on basis of analytical and ¹ H nmr spectral data. All of the bromomethylpyrazole nucleosides described showed cytostatic activity against HeLa cell sultures.     

Bicyclic nucleosides; stereoselective dihydroxylation and 2'-deoxygenation

A series of polyhydroxylated bicyclic nucleoside derivatives is approached applying stereoselective dihydroxylation reactions. Three out of four isomeric and protected products were obtained after the stereoselectivity of dihydroxylation has been completely inverted comparing a bicyclic nucleoside with a tricyclic furanose substrate. A corresponding 2'-deoxynucleoside derivative has been obtained after an optimized deoxygenation procedure.