A scalemic mixture enriched in 1-((1S,2R,4S)-4-(tert-butyldimethylsilyloxy)-2-ethylcyclopentyl)-6-tosyl-6H-pyrrolo[2,3-e][1,2,4]triazolo[4,3-a]pyrazine (9.58 g, 17.8 mmol) was dissolved in ethanol (177 mL). Concd HCl (1.75 mL, 21.3 mmol) was added dropwise. After about 1 h, EtOAc (700 mL) was added. The organic mixture was washed with saturated aqueous NaHCO3 (2×120 mL), brine (120 mL), dried over anhydrous MgSO4, filtered and concd under reduced pressure. The residue was purified using silica gel chromatography eluting with 30-100% EtOAc in DCM to give a scalemic mixture enriched in (1S,3R,4S)-3-ethyl-4-(6-tosyl-6H-pyrrolo[2,3-e][1,2,4]triazolo[4,3-a]pyrazin-1-yl)cyclopentanol (6.73 g, 89%): LC/MS (Table 1, Method b) Rt=2.11 min; MS m/z: 426 (M+H)+.
