4-Chlorobenzenesulfonyl chloride → 1,5-bis-(4-chloro-benzenesulfonyl)-6-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine

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Reaction Steps

Compound 52 from the previous step (1.1 g, 3.67 mmol) was dissolved in ethyl acetate (15 ml). HCl (g) was bubbled into the solution for 5 minutes. Solvent was removed under reduced pressure and the residue was re-dissolved in pyridine (15 ml). 4-chlorophenylsulfonyl chloride (1.55 g, 2.2 eq.) was added to the solution at zero degrees. The mixture was stirred at zero degrees and slowly raised to room temperature upon stirring overnight. Ethyl acetate (100 ml) was added to the reaction mixture, and the solution was washed with sat. NaHCO3 (2×25 ml), 10% HCl solution (2×25 ml) and brine (10 ml). Sample dried over (MgSO4), and solvent was removed under reduced pressure. The crude product was purified via flash chromatography, eluted with EtOAc/hexane (15:85) to give a white solid as the mixture of two regioisomers. LCMS 569.9 (M+23)

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