Trifluoroacetic acid → N-(4-fluorophenyl)-5-(pyridine-2-yl)pent-4-ynamide

Reaction equation

C(OC(=O)[N:7]([C:15](=[O:26])[CH2:16][CH2:17][C:18]#[C:19][C:20]1[CH:25]=[CH:24][CH:23]=[CH:22][N:21]=1)[C:8]1[CH:13]=[CH:12][C:11]([F:14])=[CH:10][CH:9]=1)(C)(C)C.FC(F)(F)C(O)=O>C(Cl)Cl.O>[F:14][C:11]1[CH:12]=[CH:13][C:8]([NH:7][C:15](=[O:26])[CH2:16][CH2:17][C:18]#[C:19][C:20]2[CH:25]=[CH:24][CH:23]=[CH:22][N:21]=2)=[CH:9][CH:10]=1

Participants

Procedure

tert-Butyl-5-(pyridin-2-yl)pent-4-ynoyl-4-fluorophenylcarbamate (299 mg, 0.81 mmol) was dissolved in DCM (4 mL) with 0.01% w/w of water. 4 mL of trifluoroacetic acid was added at room temperature to the solution. The resulting mixture was stirred at R.T. for 2 h. The solvent was removed under reduced pressure. The brown oil was dissolved in saturated NaHCO3 until pH=8. The aqueous layer was extracted with ethyl acetate. The combined organic layers were washed with brine, dried over MgSO4 and the solvent was removed under reduced pressure. The brownish solid was triturated in a mixture Et2O/Pentane: 50/50. The solid was collected by filtration and washed with a mixture Et2O/Pentane: 50/50. The solid was dried by lyophilisation to afford 181 mg of N-(4-fluorophenyl)-5-(pyridine-2-yl)pent-4-ynamide (Yield: 83%) as a colorless solid (M.P.=189.9-190.2° C.).