[CH3:1][O:2][C:3]([C:5]1[C:6]([NH2:20])=[C:7]([C:14]#[C:15][Si](C)(C)C)[CH:8]=[C:9]2[C:13]=1[NH:12][N:11]=[CH:10]2)=[O:4].[F-].C([N+](CCCC)(CCCC)CCCC)CCC.O.C(OC)(C)(C)C>O1CCCC1>[CH3:1][O:2][C:3]([C:5]1[C:6]([NH2:20])=[C:7]([C:14]#[CH:15])[CH:8]=[C:9]2[C:13]=1[NH:12][N:11]=[CH:10]2)=[O:4]To a solution of 500 mg (1.74 mmol) of 6-amino-5-trimethylsilanylethynyl-1H-indazole-7-carboxylic acid methyl ester in 17 mL of anhydrous tetrahydrofuran under an atmosphere of argon is added 2.6 mL (2.6 mmol) of a 1 M solution tetrabutylamonium fluoride in tetrahydrofuran. The reaction mixture is stirred at ambient temperature for 2 hours. Water and tert-butylmethylether are added and the two phases are separated. The aqueous layer is extracted with tert-butylmethylether. The combined organic extracts are washed with brine, dried over MgSO4 and concentrated in vacuo. The residue is suspended in hexanes. Filtration affords 210 mg (56%) of the product as a yellowish solid; LC/MS:216/217 (M+H)+.
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