Water → tert-Butyl [(1R,2S,5S)-2-amino-5-[(dimethylamino)carbonyl]cyclohexyl]carbamate oxalate

Participants

Reaction Conditions

Reaction Steps

Oxalic acid (16.24 g) was added to acetonitrile (640 ml) and water (40 ml), and the obtained solution was then heated to approximately 35° C. To this solution, a solution of tert-butyl(1R,2S,5S)-2-amino-5-[(dimethylamino)carbonyl]cyclohexylcarbamate prepared by the above described method in acetonitrile (approximately 640 ml) was added dropwise, and the obtained mixture was then stirred at approximately 35° C. for approximately 1 hour. Thereafter, the reaction solution was cooled to approximately 25° C., and was then stirred for approximately 1 hour. The precipitated crystals were filtered, and were then washed with 7% aqueous acetonitrile (300 ml) to obtain a monohydrate of the title compound (tert-butyl(1R,2S,5S)-2-amino-5-[(dimethylamino) carbonyl]cyclohexylcarbamate oxalate monohydrate). To this monohydrate of the title compound, acetonitrile (560 ml) was added, and the obtained mixture was then heated to approximately 70° C. The reaction mixture was stirred at this temperature for approximately 5 hours, and was then concentrated to approximately 320 ml. Thereafter, acetonitrile (320 ml) was added to the concentrated solution, and the obtained mixture was then cooled to approximately 25° C. The precipitated crystals were filtered and were then washed with acetonitrile (80 ml), followed by drying under reduced pressure, to obtain an anhydride of the title compound (55.74 g, yield: 82%).

Provenance & Evidence