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Synlett 2004(2): 0341-0343  
DOI: 10.1055/s-2003-44978
LETTER
© Georg Thieme Verlag Stuttgart · New York

Efficient Synthesis of O-, S-, N- and C-Glycosides of 2-Amino-2-Deoxy-d-Glucopyranose from Glycosyl Iodides

Nicolas Miquel, Stefano Vignando, Giovanni Russo, Luigi Lay*
Dipartimento di Chimica Organica e Industriale and Centro Interdisciplinare Studi Bio-molecolari e Applicazioni Industriali (CISI), Università degli Studi di Milano, via Venezian 21, 20133 Milano, Italy
Fax: +39(2)50314061; e-Mail: luigi.lay@unimi.it;
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Publication History

Received 3 October 2003
Publication Date:
08 December 2003 (online)

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Abstract

Glycosyl iodides of protected d-glucosamine are generated in situ under mild conditions and coupled with different kinds of nucleophiles, providing the corresponding β-glycosides in good yields.

Key words

carbohydrates - glycosyl iodides - glycosylations - stereo­selective synthesis

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1H NMR (Bruker Avance 400, 400 MHz, CDCl3) for compound 4: δ = 6.56 (d, 1 H, J = 10.1 Hz, H-1), 5.55 (t, 1 H, J = 9.7 Hz, H-3), 5.21 (t, 1 H, J = 9.7 Hz, H-4), 4.44 (t, 1 H, H-2), 4.28 (dd, 1 H, J = 12.5 Hz, J = 4.7 Hz, H-6), 4.15 (dd, 1 H, J = 2.3 Hz, H-6′), 3.85 (ddd, 1 H, H-5), 2.14 (s, 3 H, Ac), 2.08 (s, 3 H, Ac), 2.02 (s, 3 H, Ac), 1.99 (s, 3 H, DMM), 1.91 (s, 3 H, DMM).

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1H NMR (Bruker Avance 400, 400 MHz, C6D6, 75 °C) for compound 6: δ = 7.65-7.01 (m, 4 H, Ar), 6.90 (d, 1 H, J = 10.0 Hz, H-1), 6.02 (t, 1 H, J = 9.7 Hz, H-3), 5.38 (t, 1 H, J = 9.7 Hz, H-4), 4.98 (t, 1 H, H-2), 4.27 (dd, 1 H, J = 12.4 Hz, J = 4.7 Hz, H-6), 4.08 (dd, 1 H, J = 2.0 Hz, H-6′), 3.49 (m, 1 H, H-5), 1.88 (s, 3 H, Ac), 1.83 (s, 3 H, Ac), 1.72 (s, 3 H, Ac).

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To a solution of compound 1 and 2 (0.66 mmol, 1 equiv) in CH2Cl2 (3 mL) at 0 °C TMSI (1.1 equiv) was added under inert atmosphere. The reaction mixture was stirred at r.t. until disappearance of the starting material (about 30 min), then cooled to -78 °C. On the other hand, compound 3 (0.63 mmol, 1 equiv) was dissolved in toluene (3 mL) and TMSI (1.1 equiv) was added at 0 °C under inert atmosphere. The solution was stirred at 80 °C for 45 min, then the solvent was evaporated. The residue was dissolved in CH2Cl2 (3 mL) under inert atmosphere and the solution cooled at -78 °C. The nucleophile and the acidic promoter (when necessary, see text) were added, the solution was allowed to reach r.t. and stirred for 6-8 h. Standard workup and silica gel chromatography gave the β-glycoside. When silylated compound 2 was employed as starting material (entries 10-13 in Table [1] ), MeOH was added after glycosylation to remove the trimethylsilyl groups. After stirring 20 min, the solvent was evaporated in vacuo and the crude residue was submitted to standard acetylation.