Water → HCID 53255231, compound

Participants

Reaction Conditions

Reaction Steps

2,2,2-Trifluoroethyl N-(tert-butoxycarbonyl)-2-nitro-3-(trifluoromethoxy)-L-phenylalaninate (121) 2-Nitro-3-(trifluoromethoxy)-L-phenylalanine, hydrochloride salt (119) (250.6 mg, 0.758 mmol) was suspended in dioxane (3.5 mL)/water (3.5 mL) and the mixture was cooled to 0° C. Triethylamine (0.368 mL, 2.65 mmol) was added, resulting in a solution. BOC2O (199 mg, 0.910 mmol) was added and the mixture was stirred at 0° C. for 15 min, then allowed to warm to RT. After 2 h at RT, most of the dioxane was removed by evaporation under reduced pressure, and saturated aqueous ammonium chloride solution was added until the pH was lowered to −3. The mixture was diluted with EtOAc (10 mL), and the aqueous layer was extracted with EtOAc (3×15 mL). The combined extracts were dried over sodium sulfate, filtered and evaporated in vacuo to give N-(tert-butoxycarbonyl)-2-nitro-3-(trifluoromethoxy)phenylalanine (120), which was dissolved in dichloromethane (7 mL). 1-[3-(Dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (98%, 0.195 mL, 0.874 mmol), N,N-dimethylpyridin-4-amine (97%, 45.7 mg, 0.363 mmol) and 2,2,2-trifluoroethanol (99%, 0.106 mL, 1.46 mmol) were added and the resulting mixture was stirred for 18 h at RT. The reaction mixture was washed with saturated aqueous sodium chloride solution, and the aqueous layer was extracted with dichloromethane (3×5 mL). The combined organic layers were dried, filtered and concentrated in vacuo. Purification using silica gel chromatography (Gradient: 0% to 30% EtOAc in heptane) provided the product as a white solid (170.3 mg, 47% over 2 steps). LCMS m/z 475.4 (M−1). 1H NMR (400 MHz, DMSO-d6) δ 1.33 (s, 9H), 3.01-3.12 (m, 2H), 4.32-4.39 (m, 1H), 4.69-4.79 (m, 2H), 7.57-7.66 (m, 3H), 7.74 (dd, J=8.2, 8.2 Hz, 1H).

Provenance & Evidence