Hydrochloric Acid → 1-[2-(N-methylamino)phenyl]-1'-methylspiro[indoline-3,4'-piperidine]hydrochloride

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Reaction Steps

A solution of 2.26 g of 1-[2-(ethoxycarbonyl)aminophenyl]-1'-methylspiro[indoline-3,4'-piperidine] of Example 44 in 20 ml of dry tetrahydrofuran is added dropwise over 7 minutes to a rapidly stirred ice cold slurry of 0.94 g of lithium aluminum hydride in 10 ml of dry tetrahydrofuran under nitrogen. After heating at reflux for one hour, the reaction mixture is cooled in an ice bath and treated dropwise with 1 ml of water, 1 ml of 10% sodium hydroxide and 3 ml of water. The resultant salts are filtered and washed twice with hot chloroform. The filtrate is concentrated on a rotary evaporator and the residue is dissolved in chloroform, washed with brine, dried over anhydrous sodium sulfate, concentrated and pumped on under high vacuum to give the crude free base of the product. The free base is dissolved in 20 ml of isopropyl alcohol, cooled with an ice bath with stirring and treated dropwise with 50 ml of ethereal hydrogen chloride. The resulting clear solution is carefully concentrated to 15-20 ml and stored in a refrigerator for 2 hours, thus giving, after drying for 2 hours at 90° C. (under high vacuum), tiny needles, mp 266.5°-268.5° C., dec. Prolonged drying (24 hours) at 120° C. under high vacuum affords 1-[2-(N-methylamino)phenyl]-1'-methylspiro[indoline-3,4'-piperidine]hydrochloride, mp 271°-272° C.

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