L-Phenylalanine → (4S)-4-Benzyl-1,3-oxazolidine-2,5-dione

Participants

Reaction Conditions

Reaction Steps

A 1 L round bottom was dried in an oven prior to use (oven temp=120 ° C.). The glassware was cooled under an inert nitrogen atmosphere. Phenylalanine (50.0 g, 303 mmol) was added to the flask. Anhydrous THF (600 mL, 0.5 M) was charged to give a suspension of white solid. The mixture was heated to 50° C. and triphosgene (35.9 g, 121 mmol) was added as a solid. The suspension was stirred until the reaction was clear (−30 min). The reaction mixture was concentrated to an oil and then was slowly poured into 3 L of hexanes with rapid stirring to yield a white precipitate. The resulting suspension was capped using aluminum foil and placed in the freezer for a minimum of 3 h. The white precipitate was then filtered via vacuum filtration while maintaining an inert environment. The white solid was rinsed with hexanes (3×20 mL) to give the product. The white solid was collected and dried overnight under vacuum. 1H NMR (500 MHz, CHCl3-d): δ 7.37-7.30 (3 H, m); 7.18 (2 H, d, J=7.21 Hz); 6.23 (1 H, s); 4.53 (1 H, dd, J=8.18, 4.21 Hz); 3.27 (1 H, dd, J=14.14, 4.20 Hz); 3.00 (1 H, dd, J=14.13, 8.17 Hz).

Provenance & Evidence