Bromine → HCID 86627071, compound

Participants

Reaction Steps

To (1R,4R)-4-[(tert-butoxycarbonyl)amino]cyclopent-2-ene-1-carboxylic acid (400.00 g, 1.7601 mol; prepared in a procedure analogous to that described in Examples 1 to 3 above) dissolved in methylene chloride (6 L) was added tetrabutylammonium hydroxide in methanol (1.0M, 1800 ml), and the mixture was stirred at ambient temperature for 60 minutes. The reaction mixture was then cooled to −25° C. under a blanket of Nitrogen. Bromine (181 ml, 3.52 mol) in methylene chloride (2 L) was then added slowly over 60 minutes, maintaining an internal temperature lower than −20° C. On completion of the bromine addition, the mixture was stirred at −25° C. for a further 30 minutes, and then warmed slowly to 0° C. over 30 minutes. The mixture was then allowed to stir at 0° C. for 1 hour. At 0° C., a mixture of L-ascorbic acid sodium salt (523.0 g, 2.640 mol) in water (3 L) and saturated sodium bicarbonate in water (3 L), was added slowly over 30 minutes maintaining an internal temperature lower than 10° C. The resulting bi-phasic mixture was stirred and allowed to warm to ambient temperature over 1 hr. The methylene chloride layer was separated and the aqueous layer was extracted with methylene chloride (2 L). The methylene chloride layers were combined and concentrated to a volume of about 4 L. Ethyl acetate (8 L) was added, and the mixture was concentrated to a volume of about 5 L. Ethyl acetate (5 L) was added, and the resulting mixture was washed 3 times with water (4 L). The organic layer was then washed with saturated sodium chloride in water (2 L) and concentrated to afford the title compound (460 g, 85%) as a white solid. 1H NMR (300 MHz, CDCl3): δ 5.09 (d, 1H), 4.80 (m, 1H), 4.71 (m, 1H), 4.47 (m, 1H), 4.04 (m, 1H), 2.39 (m, 1H), 1.89 (m, 1H) and 1.46 (bs, 9H).

Provenance & Evidence