Triphenylphosphine dibromide → Tert-butyl 3-(5-(3-amino-6-bromopyrazin-2-yl)-1,3,4-oxadiazol-2-yl)benzylcarbamate

Participants

Reaction Steps

3-amino-6-bromo-pyrazine-2-carbohydrazide (1.2 g, 5.172 mmol), TBTU (1.333 g, 5.689 mmol), 3-[(tert-butoxycarbonylamino)methyl]benzoic acid (1.300 g, 5.172 mmol) and DIPEA (1.338 g, 1.803 mL, 10.35 mmol) in a solution in DMF (13.98 mL) were stirred at room temperature for 1 h. The reaction mixture was diluted with ethyl acetate (35 mL), washed with water (2×50 mL) and brine (1×50 mL). The organic layer was dried over MgSO4 and concentrated in vacuo to a solid. This solid was suspended in MeCN (83.89 mL) at room temperature followed by the addition of dibromo(triphenyl)phosphorane (2.183 g, 5.172 mmol) and DIPEA (1.338 g, 1.803 mL, 10.35 mmol). The resulting mixture was stirred at room temperature for 2 h and then concentrated in vacuo to leave a solid. This was purified by column chromatography on silica eluting with EtOAc/petroleum ether, Product fractions were combined and concentrated in vacuo to leave the product as a white solid. The mixture was conc. to a solid and purified by column chromatography using ethylacetate/pet ether as elaunt to afford the product as a white solid (924 mg, 40% yield); 1H NMR (400 MHz, DMSO) d 1.43 (s, 9H), 4.26 (m, 2H), 7.55 (m, 3H), 7.80 (br s, 2H), 7.97 (m, 1H) and 8.45 (s, 1H) ppm; MS (ES+) 449.08

Provenance & Evidence