1,1'-Carbonyldiimidazole (1.7Kg, 10.48mol) and THF (7.5L) were added to a 22L flask and solid pyridinecarboxylic acid (1.36Kg, 11 mol) was added to the slurry at room temperature, the reaction was heat absorbed and the mixture was allowed to cool down from 18C to 12C, then the reaction mixture was heated to 18-19C. The resulting clarified solution was stirred for 1 h and (1S,2S)-(+)-1,2-diaminocyclohexane (0.5 Kg, 4.38 mol) was added within 1 h while keeping the temperature lower than 50 C, the beaker and funnel were rinsed with 2.5 L of THF, the reaction was stirred at room temperature for 15 h. Water (0.5 L) was added to the dilute slurry to obtain a clarified solution and the reaction mixture was The reaction mixture was stirred for 1 h. The reaction mixture was concentrated to an orange semi-solid by rotary evaporation, and the reaction product was slurried in 5 L of ethanol and concentrated by rotary evaporation, dissolved in ethanol (5 L) at 64-65 C, cooled, and the solution became turbid at about 58 C. The turbid solution was inoculated (10 g) at this temperature and cooled to -8C. The resulting white crystals were separated by filtration over a sintered glass funnel and washed with 5 L of cold water. ethanol (-8 to -10C), purged with nitrogen under room vacuum and then dried in a vacuum oven (35C). This resulted in the isolation of 1.23 Kg (86.3%) of white crystalline solid.
