To a scalemic mixture enriched in (1R,3R,4S)-3-ethyl-4-(6-tosyl-6H-pyrrolo[2,3-e][1,2,4]triazolo[4,3-a]pyrazin-1-yl)cyclopentyl 4-nitrophenyl carbonate (0.211 g, 0.357 mmol) in 1,4-dioxane (1.5 mL) was added cyclopropanamine (0.102 g, 1.786 mmol). After about 1 h, aqueous NaOH (1N, 1.5 mL, 1.5 mmol) was added and the reaction mixture was heated at about 60° C. for about 30 min then cooled to ambient temperature. The reaction mixture was extracted with DCM (3×5 mL). The combined organic solvents were concd under reduced pressure. The residue was purified using silica gel chromatography eluting with 0-100% EtOAc:MeOH (9:1) in EtOAc to give (1R,3R,4S)-3-ethyl-4-(6H-pyrrolo[2,3-e][1,2,4]triazolo[4,3-a]pyrazin-1-yl)cyclopentyl cyclopropylcarbamate (0.0847 g, 67%): LC/MS (Table 1, Method b) Rt=1.73 min; MS m/z: 355 (M+H)+.
