Triphenylphosphine dibromide → 5-Bromo-3-(5-(thiophen-2-yl)-1,3,4-oxadiazol-2-yl)pyrazin-2-amine

Participants

Reaction Steps

3-amino-6-bromo-pyrazine-2-carboxylic acid (3.2 g, 14.68 mmol) and thiophene-2-carbohydrazide (2.152 g, 14.68 mmol) were suspended in acetonitrile (48.00 mL) at room temperature and dibromo(triphenyl)phosphorane (24.79 g, 58.72 mmol) was added, followed byadditional acetonitrile (16.00 mL). The reaction mixture turned bright yellow in colour and was stirred at room temperature for 1 h. After this time, the reaction mixture cooled in an icebath and DIPEA (7.209 g, 9.716 mL, 55.78 mmol) was added dropwise. The reaction mixture was stirred in the ice bath for 1 h and then additional DIPEA (2.277 g, 3.069 mL, 17.62 mmol) added and the reaction mixture stirred for left for 30 mins and further DIPEA (1.897 g, 2.557 mL, 14.68 mmol) added. The reaction mixture was stirred for 1 h and then filtered. The solid was washed with ether, isolated and then triturated with acetonitrile and washed with ether to give the product as a yellow solid (2.776 g, 57% yield); 1H NMR (400.0 MHz, DMSO) 7.35 (s, 1H), 7.80 (br s, 2H), 7.98 (m, 1H), 8.04 (m, 1H) and 8.45 (s, 1H); MS (ES+) 326.04

Provenance & Evidence