N1C=CC=CC=1.[F:7][C:8]1[C:17]2[O:16][CH2:15][CH:14]([C:18]([NH2:20])=O)[O:13][C:12]=2[CH:11]=[CH:10][CH:9]=1.FC(F)(F)C(OC(=O)C(F)(F)F)=O>O1CCOCC1.CCOCC>[F:7][C:8]1[C:17]2[O:16][CH2:15][CH:14]([C:18]#[N:20])[O:13][C:12]=2[CH:11]=[CH:10][CH:9]=113.7 ml of pyridine (169 mmol, 2 eq.) are added to a suspension of 16.7 g of amide from Stage 1 (84.5 mmol) in 180 ml of dioxane at 0° C., followed, 10 minutes later, by dropwise addition of 13.1 ml of trifluoroacetic anhydride (19.5 g; 93 mmol, 1.1 eq.). The reaction mixture is kept cold for 1 hour and is then stirred at room temperature for 16 hours. The solution is taken up in Et2O/1N HCl. The organic phase is washed with 1N NaOH, dried over MgSO4, filtered and then evaporated to dryness. 16.8 g of a pale yellow oil are obtained (quantitative yield).
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