Step AAH (7): To a soln of 7-phenyl-4,5-dihydropyrazolo[1,5-a]pyridin-2-ol (500 mg, 2.356 mmol) in THF (15 mL) was added NaHMDS (1.0 M in THF, 2.94 mL, 2.94 mmol) at −78° C. under nitrogen. After stirring for 10 min, 1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonyl fluoride (1281 mg, 4.24 mmol) was added. The mixture was allowed to warm from −78° C. to rt over 3 h. The reaction was diluted with EtOAc (200 mL) and washed sequentially with 0.1 N aqueous sodium hydroxide, water, and brine. The organic layer was dried over Na2SO4, filtered, and concentrated in vacuo. The residue was purified using silica gel column chromatography (30% EtOAc/hexanes) to afford 7-phenyl-4,5-dihydropyrazolo[1,5-a]pyridin-2-yl 1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonate (1.0 g, 86% yield). LC-MS (M+H)+ 495.12.
