[CH3:1][O:2][C:3]([C:5]1[C:10]([NH:11][C:12]2[CH:17]=[CH:16][C:15]([Si:18]([CH3:21])([CH3:20])[CH3:19])=[CH:14][C:13]=2[F:22])=[N:9][C:8]([CH2:23][NH2:24])=[CH:7][N:6]=1)=[O:4].[C:25](OC(=O)C)(=[O:27])C>C(O)=O>[CH3:1][O:2][C:3]([C:5]1[C:10]([NH:11][C:12]2[CH:17]=[CH:16][C:15]([Si:18]([CH3:19])([CH3:20])[CH3:21])=[CH:14][C:13]=2[F:22])=[N:9][C:8]([CH2:23][NH:24][CH:25]=[O:27])=[CH:7][N:6]=1)=[O:4]A solution of 5-aminomethyl-3-(2-fluoro-4-trimethylsilanyl-phenylamino)-pyrazine-2-carboxylic acid methyl ester (800 mg, 2.30 mmol) from above in formic acid (12 mL) and acetic anhydride (4 mL) was stirred at ambient temperature under N2 for 1.5 hour. The reaction mixture was concentrated in vacuo, and the residue was azeotroped with toluene. The resultant residue was diluted with ethyl acetate. The organic layer was washed with saturated aqueous solution of sodium bicarbonate, water and brine, dried (Na2SO4), filtered and concentrated in vacuo to afford the title compound as a yellow foam (850 mg, 98.3%). LCMS (method D1): RT=1.09 min, [M+H]+=377.
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