Sodium Hydroxide → Ammonium Hydroxide

Participants

Reaction Steps

To a solution of 3.09 g of 1-[N-benzyloxycarbonyl-(S)-alanyl]azacyclooctane-2(R,S)-carboxylic acid, ethyl ester in 150 ml methanol, add 20 ml of 2.5 N sodium hydroxide and stir the mixture at room temperature for 18 hours. Concentrate the mixture under nitrogen, dilute the residue with ice-water and then make the mixture acidic with concentrated hydrochloric acid. Extract the aqueous solution with ethyl acetate and dry the organic phase over magnesium sulfate. Concentrate the organic phase to give a white residue. Place the residue on a column of silica gel (1000 ml, 60-200 mesh) and elute with chloroform:isopropanol:7% NH4OH (organic phase) to give 1-[N-benzyloxycarbonyl-(S)-alanyl]azacyclooctane-2(R)-carboxylic acid and 1-[N-benzyloxycarbonyl-(S)-alanyl]azacyclooctane-2(S)-carboxylic acid, as colorless oils.

Provenance & Evidence