Trichloroisocyanuric Acid → (2R)-4-((tert-butoxy)carbonyl)morpholine-2-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

Satd aq NaHCO3 (15 mL) was added to a solution of (R)-tert-butyl 2-(hydroxymethyl)-morpholine-4-carboxylate (1.09 g, 5.0 mmol) in acetone (50 mL), stirred and maintained at 0° C. Solid NaBr (0.1 g, 1 mmol) and TEMPO (0.015 g, 0.1 mmol) were added. Trichloroisocyanuric acid (2.32 g, 10.0 mmol) was then added slowly within 20 min at 0° C. After addition the mixture was warmed to rt and stirred overnight. 2-Propanol (3 mL) was added, and the resulting solution was stirred at rt for 30 min, filtered through a pad of Celite, concentrated under vacuum, and treated with satd aq Na2CO3 (15 mL). The aqueous solution was washed with EtOAc (5 mL), acidified with 6 N HCl, and extracted with EtOAc (5×10 mL). These EtOAc extracts were combined, dried over Na2SO4 and concentrated to give (R)-4-(tert-butoxycarbonyl)morpholine-2-carboxylic acid (1.07 g, 92%) as a white solid. 1H NMR (400 MHz, CDCl3): 4.20 (br, 1 H), 4.12 (d, 1 H), 4.02 (d, 1 H), 3.84 (m, 1 H), 3.62 (m, 1 H), 3.04 (m, 2 H), 1.44 (s, 9 H); MS m/z 232 (M+H+).

Provenance & Evidence