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, 1 H‐NMR and 13 C‐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 4 H 5− and 3 a flattened 4 H 5 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 NH 3 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 NH 3 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 NO 2 group to give the 3‐azidomannoheptulose 35 in high yields ( Scheme 4).