Boron tribromide → 4-[(4-Bromo-2-furyl)methyl]-3-{4-[(2-hydroxyethyl)amino]-1,2,5-oxadiazol-3-yl}-1,2,4-oxadiazol-5(4H)-one

Participants

Reaction Conditions

Reaction Steps

In a round bottom flask under nitrogen atmosphere, 4-[(4-bromo-2-furyl)methyl]-3-{4-[(2-methoxyethyl)amino]-1,2,5-oxadiazol-3-yl}-1,2,4-oxadiazol-5(4H)-one (8.2 g, 21 mmol) was stirred in dichloromethane (68 mL). The temperature was brought to −78° C. and a solution of 1.0 M boron tribromide in dichloromethane (43 mL, 43 mmol) was added dropwise over 45 minutes. The reaction stirred at −78° C. for 45 minutes and continued to stir at 0° C. for an additional 30 minutes. While remaining at 0° C., a saturated solution of sodium bicarbonate in water (120 mL) was added dropwise over 25 minutes. After warming to room temperature, the organic layer was collected and the aqueous layer was extracted with ethyl acetate (2×50 mL). The combined organic layers were washed with brine (100 mL), dried over sodium sulfate and concentrated in vacuo to give the desired product (7.7 g, 97%) along with a small amount of 3-{4-[(2-bromoethyl)amino]-1,2,5-oxadiazol-3-yl}-4-[(4-bromo-2-furyl)methyl]-1,2,4-oxadiazol-5(4H)-one. LCMS calculated for C11H13BrN5O5 (M+H)+: m/z=371.7, 374.0. 1H NMR (400 MHz, DMSO-d6): δ 7.89 (s, 1H), 6.68 (s, 1H), 6.31 (t, J=5.8 Hz, 1H), 5.08 (s, 2H), 4.85 (br s, 1H), 3.56 (m, 2H), 3.30 (q, J=5.6 Hz, 2H).

Provenance & Evidence