Dimethylformamide → 5-chloro-1H-indazole-7-carbaldehyde

Participants

Reaction Steps

7-Bromo-5-chloro-1H-indazole (0.44 g, 1.90 mmol) and sodium hydride were combined in tetrahydrofuran (5 mL) at 0° C. After 15 min, cooling was removed and the mixture stirred at room temperature for 20 min. The stirred mixture was cooled to −78° C. and treated with a solution of tert-butyllithium in pentane (1.7 M, 2.4 mL, 3.99 mmol) over several minutes. The mixture was allowed to gradually warm to −20° C. over 1 h, re-cooled to −78° C. and treated with dimethylformamide (220 μL, 2.85 mmol). The reaction was warmed to 0° C. over several hours, then treated with saturated ammonium chloride. The reaction was diluted with ethyl acetate. The layers were separated. The organic layer was washed with brine (2×), dried over sodium sulfate, filtered and concentrated to afford 0.3 g (87%) as a white powder. LC/MS (HPLC method 1): tR=1.88 min, 181.02(MH)+.

Provenance & Evidence