[N:1]1[CH:6]=[CH:5][C:4]([CH2:7]P(=O)(OCC)OCC)=[CH:3][CH:2]=1.C(O[K])(C)(C)C.[CH:22]([C:24]1[C:32]2[C:27](=[CH:28][C:29]([C:33]#[N:34])=[CH:30][CH:31]=2)[NH:26][N:25]=1)=O>CN(C=O)C>[N:1]1[CH:2]=[CH:3][C:4](/[CH:7]=[CH:22]/[C:24]2[C:32]3[C:27](=[CH:28][C:29]([C:33]#[N:34])=[CH:30][CH:31]=3)[NH:26][N:25]=2)=[CH:5][CH:6]=1Diethyl pyridin-4-ylmethylphosphonate was redissolved in DMF (25 mL) and cooled to 0° C. tBuOK (3.36 g, 30 mmol) was added portion wise over 2 min and the reaction mixture turned dark brown red. After stirring for 2 min at 0° C., a solution of 3-formyl-1H-indazole-6-carbonitrile (1.71 g, 10 mmol) in DMF (15 mL) was added dropwise by pipette over 5 min. The resulting mixture was stirred for 40 min at 0° C. before quenching with ice, 2N HCl (20 mL) and H2O (20 mL). After stirring for 10 min at rt, the reaction mixture was carefully basified with sat. NaHCO3 to pH about 8 and copious amounts of yellow precipitate formed. The solid was collected by suction filtration and rinsed with H2O. After dying under high vacuum, 2.016 g (82%) of title compound was obtained as beige solid. 1H NMR (400 MHz, DMSO-d6) δ 13.90 (s, 1H, NH), 8.60-8.54 (m, 2H), 8.43 (d, J=8.0 Hz, 1H), 8.20 (s, 1H), 7.93 (d, J=16.0 Hz, 1H), 7.70 (d, J=4.0 Hz, 2H), 7.58 (d, J=8.0 Hz, 1H, partially overlapping with the doublet at 7.55 ppm), 7.55 (d, J=16.0 Hz, 1H, partially overlapping with the doublet at 7.58 ppm); MS ESI 250.0 [M+H]+, calcd for [C15H11N3O+H]+ 250.1.
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