Epimerisation of Carbohydrates and Cyclitols, 17.1 Synthesis of Glycosyl Azides and N-Acetyl Glycosyl Amines of Rare Monosaccharides

Christian Hager; Ralf Miethchen; Helmut Reinke

doi:10.1055/s-2000-6250

Synthesis 2000; 2000(2): 226-232
DOI: 10.1055/s-2000-6250

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Epimerisation of Carbohydrates and Cyclitols, 17.¹ Synthesis of Glycosyl Azides and N-Acetyl Glycosyl Amines of Rare Monosaccharides

Christian Hager^* , Ralf Miethchen, Helmut Reinke

^*Universität Rostock, Lehrstuhl Organische Chemie II, Buchbinderstrasse 9, D-18051 Rostock, Germany; Fax +49 (3 81) 4 98 18 19; E-mail: ralf.miethchen@chemie.uni-rostock.de

Abstract

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The glycosyl azides 1 (d-arabino), 3 (l-fuco), 5 (d-manno), and 7 (d-galacto) were epimerised in a one-pot procedure by heating with chloral/DCC/1,2-dichloroethane in good yields. The respective products, epimerised at the C-3 atom, have d-lyxo (2), l-gulo (4), d-altro (6), and d-gulo (8, 9) configuration. Compound 8, directly generated or obtained by deformylation of its 6-O-formyl derivative 9, was used as the key intermediate for further syntheses. Besides the acetylation of 8 to 10, and decarbamoylation to the 4,6-dihydroxy derivative 11, the latter 11 was acetylated to 12 and benzylated to 13. Moreover, the azide function of 8 was converted into an amino group using tributyltin hydride/AIBN or Staudinger conditions. The amino derivatives were isolated in the form of their N-acetyl derivatives 14 and 15, respectively. Finally, the dichloroethylidene (14) and the trichloroethylidene (15) groups were hydrodechlorinated forming the same ethylidene derivative 16. Crystal structures are given for the gulopyranoses 4 and 12.

carbohydrates - azides - acetals - amides - stereoselectivity

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