Hydrochloric Acid → Ethyl[(3,4-dihydro-1'-[2-(benzofurazan-5-yl)ethyl]-4-oxo-spiro[(2H)-1-benzopyran-2,4'-piperidine]-6-yl)amino]sulfonyl acetate hydrochloride

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Reaction Steps

Ethyl chlorosulfonylacetate (140 mg, 0.75 mmol) in DMF (1 ml) was added dropwise to a stirred solution of 6-amino-3,4-dihydro-1'-[2-(benzofurazan-5-yl)-ethyl]-spiro[(2H)-1-benzopyran-2,4'-piperidine]-4-one (189 mg, 0.5 mmol) and pyridine (40 mg, 3 mmol) in DMF (5 ml). The mixture was stirred for 4 hours, then additional ethyl chlorosulfonylacetate (46 mg, 0.25 mmol) was added. The mixture was stirred for 1 hour, poured into aqueous sodium hydrogen carbonate (saturated, 25 ml) and extracted with dichloromethane (3×25 ml). The combined organic fractions were dried (Na2SO4) and evaporated under reduced pressure. The residue was purified by flash column chromatography on silica gel, eluting with CH2Cl2 /MeOH/NH3 (Aq.). (97:3:0.3) to give a yellow foam which was dissolved in ethyl acetate (2 ml) and treated with ethanolic HCl (6N, 0.5 ml). The mixture was stirred for 1 hour, cooled and the solid was collected and dried in vacuo to give the hydrochloride as a white solid (171 mg, 61%), m.p. 250°-251° C.

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