Atenolol → Esatenolol

In order to prevent the reaction of produced atenolol with the optically active glycidyl ether (4) it is preferable to add the optically active glycidyl ether (4) to isopropyl amine in a solvent. The removal of excess isopropyl amine by distillation gave desired (S)-atenolol (1). Preferably, the distillation is carried out at atmospheric pressure at the initial stages and under reduced pressure at later stages, keeping the reaction mass temperature below 60° to 70° C., through out the distillation process. The crude residue may be purified, if required, by dissolving it in 1N HCl, treating this solution with activated charcoal, filtering the charcoal followed by treatment of alkali to precipitate the product. Thus, the solid product was isolated by conventional method such as filtration to get (S)-atenolol (1) of optical purity of 98% ee and above. If, necessary, the optically active (S)-atenolol (1) may be crystallized from an appropriate solvent such as water, alcohols, such as methanol, ethanol, isopropyl alcohol, butanol etc., ethers, such as diethyl ether, methyl tbutyl ether, diisopropyl ether or ketones, such as acetone, ethyl methyl ketone, methyl isobutyl ketone etc.