Oxalyl chloride (146.89 mL, 1.69 mol) is added over 15 min to a stirred solution of (1R,2S)-2-cyclohexyl-1-(4-cyclopropanesulfonyl-phenyl)-cyclopropanecarboxylic acid (295.00 g, 0.847 mol) in 10 L of anhydrous dichloromethane under an inert atmosphere. Dimethylformamide (654.61 μL, 8.5 mmol) is then added at once, and the resulting solution is stirred overnight. Volatiles are then removed under vacuum at 40° C. to afford an oil, which is dissolved in 3 L of anhydrous dichloromethane. An inert atmosphere is reestablished, and the solution is cooled to <5° C. Triethylamine (177 mL 1.27 mol) is then added dropwise over 20 minutes, leaving a dark solution. Sodium Sulfate (120.25 g, 0.847 mol) is added, followed by 5-(2-pyrrolidin-1-yl-ethylsulfanyl)-thiazol-2-ylamine (213.60 g 0.931 mole). The internal temperature rises to 20° C. The reaction mixture is stirred for 10 min in the cold, and is then allowed to warm to room temperature. After being stirred overnight, the reaction mixture is poured onto 3 L of water. The resulting mixture is stirred for a few minutes, and then the two layers are separated. The aqueous layer is extracted with 1 L dichloromethane, and the dichloromethane solutions are combined, dried over MgSO4, filtered, and concentrated under vacuum at 40° C. The resulting oil (556 g) is applied to silica gel plugs as a dichloromethane solution. Elution of the plugs with 1:12:7 2M ammonia in methanol/methyl t-butyl ether/heptane, followed by 1:19 2M ammonia (in methanol)/ethyl acetate affords a brown foam (351 g). Crystallization of 320 g of this material from methyl t-butyl ether and heptane, affords the title compound (279.4 g) as an off-white solid after drying for 2 days at 45° C. LCMS (m/e): 560 (M+H); [α]D20=−44°.
