Desoxy‐nitrozucker 14. Mitteilung 1‐C‐Nitroglycale. Herstellung und Umsetzung mit einigen Stickstoff‐Nucleophilen

1‐C‐Nitroglycals. Preparation and Reaction with Some Nitrogen Nucleophiles Acetylation of the 1‐deoxy‐1‐nitromannopyranoses 2 and 6 was accompagnied by spontanous β‐elimination to give the 1‐C‐nitroglucals 3 and 7, respectively, while acetylation of the gluco‐ and galacto‐configurated 1‐deoxy‐1‐nitropyranoses 8 and 14 gave the acetates 9 and 15, respectively (Scheme 1). The acetylation of the ribo‐ and arabino‐configurated 1‐deoxy‐1‐nitrofuranoses 19 and 21 also occurred without β‐elimination to give the acetates 20 and 22, respectively (Scheme 2). Mild base treatment of the previously described O‐acetylnitro‐β‐D‐glucose 4, the O‐acetylnitro‐β‐D‐pyranoses 9 and 15, and the O‐acetylnitro‐β‐D‐furanoses 17, 20, and 22 gave the 1‐C‐nitroglycals 3, 10, 16, 18 and 23, respectively (Scheme 1 and 2). The previously obtained 1‐C‐nitroglucal 3 was deacetylated by treatment with MeOH in the presence of KCN or sodium m‐nitrophenolate to give the free nitroglucal 5. Deacetylation of the benzylidene protected 1‐C‐nitroglucal 10 (MeOH, NaOMe) gave the 4,6‐O‐benzylidene‐1‐C‐nitroglucal 11 and traces of the 2‐O‐methyl‐1‐C‐nitromannoses 12 and 13. The UV, IR, 1H‐NMR and 13C‐NMR spectra of the 1‐C‐nitroglycals are discussed. In solution, the 1‐C‐nitroglycals 1, 5, 7, 10, 11, and 16 adopt approximately a 4H5− and 3 a flattened 4H5 conformation. The structure of 5 was established by X‐ray analysis. In the solid state, 5 adopts a sofa conformation, which is stabilized by an intramolecular H‐bond. The β‐addition of NH3 to the 1‐C‐nitroglucals 7 and 10 was followed by an O→ N acetyl migration to give exclusively anomeric pairs of the N‐acetyl‐1‐nitromannosamine derivatives 24/25 and 26/27, respectively (Scheme 3). The β‐addition of methylamine, octadecylamine, and tryptamine to the 1‐C‐nitroglucal 11 also stereoelectronically controlled and gave the crystalline N‐alkyl‐1‐nitromannosamines 28, 29, and 30, respectively. The stereoelectronically controlled β‐addition of NH3 to the 1‐C‐nitrogalactal 16, followed by acetylation, yielded exclusively the talosamine derivative 31, while the reversible β‐addition of azide ions to 16 gave the anomeric 2‐azido‐1‐nitrogalactoses 32 and 33. The β‐addition of azide ions to the 1‐C‐nitroglucal 1 led to the 2‐azido‐1‐nitromannose 34. In the presence of excess formaldehyde, this addition was followed by a Henry reaction. Chromatography of the crude product was accompagnied by solvolytic removal of the NO2 group to give the 3‐azidomannoheptulose 3