Patent ID: 7939680

Claim:
A process for the preparation of Escitalopram of Formula I, which comprises, (i) reacting the diol compound (VI), with oxalic acid in an organic solvent to get crystalline oxalate salt of (±)-4-[4-(dimethylamino)-1-(4-fluorophenyl)-1-hydroxybutyl]-3-(hydroxymethyl)-benzonitrile [(±)-Diol oxalate] (VIa), (ii) isolating the crystalline Diol oxalate (VIa) by filtration and neutralizing the oxalate salt to get pure diol compound (VI), (iii) separating the enantiomers from the pure Diol compound (VI) with an optically active acid precipitant to obtain (S)-(−)-4-[4-(dimethylamino)-1-(4-fluorophenyl)-1-hydroxybutyl]-3-(hydroxymethyl)benzonitrile (VII), (iv) cyclizing the (S)-(−)-Diol (VII) in an organic solvent in the presence of sulfonyl halide and a base to produce Escitalopram (I).