El Ashry, El Sayed H. and El Tamany, El Sayed H. and Fattah, Mohy El Din Abdel and Aly, Mohamed R. E. and Boraei, Ahmed T. A. and Duerkop, Axel (2013) A new synthetic access to 2-N-(glycosyl)thiosemicarbazides from 3-N-(glycosyl)oxadiazolinethiones and the regioselectivity of the glycosylation of their oxadiazolinethione precursors. BEILSTEIN JOURNAL OF ORGANIC CHEMISTRY, 9. pp. 135-146. ISSN 1860-5397,
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Glycosylations of 5-(1H-indol-2-yl)-1,3,4-oxadiazoline-2(3H)-thione delivered various degrees of S- and/or N-glycosides depending on the reaction conditions. S- Glycosides were obtained regiospecifically by grinding oxadiazolinethiones with acylated alpha-D-glycosyl halides in basic alumina, whereas 3-N-(glycosyl)oxadiazolinethiones were selectively obtained by reaction with HgCl2 followed by heating the resultant chloromercuric salt with alpha-D-glycosyl halides in toluene under reflux. On using Et3N or K2CO3 as a base, mixtures of S- (major degree) and N-glycosides (minor degree) were obtained. Pure 3-N-(glycosyl)oxadiazolinethiones can also be selectively obtained from glycosylsulfanyloxadiazoles by the thermal S -> N migration of the glycosyl moiety, which is proposed to occur by a tight-ion-pair mechanism. Thermal S -> N migration of the glycosyl moiety can be used for purification of mixtures of S- or N-glycosides to obtain the pure N-glycosides. The aminolysis of the respective S- or N-glycosides with ammonia in aqueous methanol served as further confirmation of their structures. While in S- glycosides the glycosyl moiety was cleaved off again, 3-N-(glycosyl)oxadiazolinethiones showed a ring opening of the oxadiazoline ring (without affecting the glycosyl moiety) to give N-(glycosyl)thiosemicarbazides. Herewith, a new synthetic access to one of the four classes of glycosylthiosemicarbazides was found. The ultimate confirmation of new structures was achieved by X-ray crystallography. Finally, action of ammonia on benzylated 3-N-(galactosyl)oxadiazolinethione unexpectedly yielded 3-N-(galactosyl) triazolinethione. This represents a new path to the conversion of glycosyloxadiazolinethiones to new glycosyltriazolinethione nucleosides, which was until now unknown.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | HETEROCYCLIC-COMPOUNDS; DERIVATIVES; GLYCOPROTEINS; NUCLEOSIDES; INHIBITORS; GLYCOSIDES; GLUCOSIDES; glycosyloxadiazolinethiones; glycosylsulfanyloxadiazoles; glycosylthiosemicarbazides; thermal rearrangement; X-ray crystallography |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Analytische Chemie, Chemo- und Biosensorik Chemistry and Pharmacy > Institut für Analytische Chemie, Chemo- und Biosensorik > Chemo- und Biosensorik (Prof. Antje J. Bäumner, formerly Prof. Wolfbeis) |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 28 Apr 2020 06:24 |
| Last Modified: | 28 Apr 2020 06:24 |
| URI: | https://pred.uni-regensburg.de/id/eprint/17280 |
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