2,5-Dichloronitrobenzene → Escitalopram

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반응 단계

To a solution of 64 Kg of (S)-(−)-4-[4-(dimethylamino)-1-(4-fluorophenyl)-1-hydroxy-1-butyl]-3-(hydroxymethyl)benzonitrile in 300 lit DMSO was added 77.48 Kg of anhydrous K2CO3 and 43.06 Kg of 2,5-dichloronitrobenzene at room temperature and stirred for 16 hours at 100-105° C. To the reaction mixture 3000 ml of water was added at about 30° C. The reaction mixture was extracted with toluene, the toluene layer was washed with water and 5% sodium hydroxide solution and after acid base treatment yielded an oily product. The oil was dissolved in 510 lit of isopropanol at about 30° C. and 20.4 lit water added, stirred for 10 minutes and 20.8 Kg of oxalic acid dihydrate was added and heated to about 70-75° C., stirred, charcolised, cooled and filtered. The filtrate was cooled to 5-10° C. slowly and the resultant solid was filtered, dried at 60° C. and micronised to get the oxalic acid salt of (S)-(+)-1-[3-(dimethylamino)propyl]-1-(4-fluorophenyl)-1,3-dihydro-5-isobenzofuran carbonitrile.

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