Hydrochloric Acid → (3S,4R,5S,6R)-3-amino-6-(hydroxymethyl)oxane-2,4,5-triol hydrochloride

Participants

Reaction Conditions

Reaction Steps

The crude mixture of N-benzyl-2-amino-2-deoxy-D-mannose and N-benzyl-2-amino-2-deoxy-D-glucose obtained according to example 2A was suspended in methanol (20-100 mL), and the pH was adjusted to approximately 1-2 with HCl (10-40 mL 2M HCl and additional 2-8 mL conc. HCl). 10% Pd on charcoal (0.4-1.6 g) was added and the reaction mixture was stirred at r.t. or at 45° C. under H2-atmosphere (up to 5 bar) until all the starting material was consumed. The reaction mixture was filtered through Celite® and washed with 20-50 mL of methanol:water (2:1). The solvents were evaporated until approx. 20-40 mL of volume remained. The crystallization of glucosamine hydrochloride was initiated by adding methanol (40-80 mL) to the aqueous sugar solution and kept at 0-5° C. for overnight. The crystals were separated by filtration and washed with cold methanol. Methanol from the mother liquor was evaporated, and to the remaining aqueous solution 20-80 mL isopropanol was added. The solution was kept at 0-5° C. overnight, the crystals formed were filtered, washed with cold isopropanol and dried: 3.9 g of D-mannosamine hydrochloride was isolated.

Provenance & Evidence