Hydrochloric Acid → Ammonium Hydroxide

Participants

Reaction Steps

To a solution of the product of Step A (4.3 g, 12 mmol) in methanol (25 mL) was added aqueous 2N NaOH (10 mL) and the reaction mixture was stirred at room temperature. The rapid progress of mono-deesterification was monitored by TLC analysis using CHCl3 --MeOH--NH4OH:(80:15:1). After 15 min, the reaction mixture was cooled to 0° C. and neutralized with aqueous 2N HCl. Methanol was removed in vacuo and the resulting mixture was acidified with aqueous 2N HCl. The oily product which precipitated was extracted into methylene chloride (3×40 mL) and the combined organic phase was washed with water, brine and then dried over MgSO4. Removal of the solvent in vacuo afforded the crude product which was then purified by flash-chromatography on silica gel using CHCl3 --MeOH--NH4OH:(80:10:1) to give desired product as the ammonium salt. The salt was treated with aqueous 1N HCl (20 mL) to provide the titled compound as a white solid (3.4 g).

Provenance & Evidence