Sodium Hydroxide → (S)-2-((S)-2-((tert-Butoxycarbonyl)amino)-4-methylpentanamido)-4-methylpentanoic acid

Participants

Reaction Steps

A solution of NaOH (1.34 g, 33.5 mmol) in water (15.0 g) was added dropwise over 10 min to the solution of Boc-Leu-Leu-OMe (10.0 g, 27.9 mmol) in acetone (20.0 g) and water (50.0 g) at 18-22° C. The reaction mixture was stirred at this temperature for 1 h and then analyzed by HPLC. When the methyl ester is under 5%, the reaction stirred for an additional 0.5 h. A white turbidity formed by the end of the reaction which was removed by filtration and rinsed with water (5.0 g). The clear filtrate was treated with formic acid (ca 0.8 g) to form a cloudy solution followed by immediate crystallization of product. Additional formic acid (1.5 g) was added (to pH 4.0-4.5) and the resulting product was collected by filtration then was washed by a mixture of acetone (10.0 g) and water (40.0 g). The solid product was suspended in a mixture of acetone (14.0 g) and water (56.0 g) for 15 min. The solid was collected by filtration and washed with a mixture of acetone (7.5 g) and water (30.0 g) and dried in vacuo at 45° C. Yield: 8.6-8.8 g (89.6-91.7%).

Provenance & Evidence