3,4-dihydro-2H-pyran → 5-bromo-1-(oxan-2-yl)-1H-indazole

Participants

Reaction Steps

A 250-mL round-bottom flask equipped with a magnetic stir bar, a rubber septum, and a N2 inlet was charged with 5-bromo-1H-indazole (10 g, 50.7 mmol) and anhydrous DCM (101 mL). To this solution, DHP (23 mL, 253.8 mmol) was added in one portion at room temperature followed by addition of PPTS (1.28 g, 5 mmol). The resulting mixture was stirred at room temperature for 48 h. Upon completion by TLC, the reaction mixture was quenched with water and extracted with DCM (3×100 mL). The combined organic extracts were washed with water (100 mL), washed with brine (50 mL), dried over sodium sulfate, filtered, concentrated, and purified by silica gel chromatography (0-10% ethyl acetate in hexanes) to give the title compound (13 g) as a pale yellow oil. 1H NMR (300 MHz, DMSO-d6): δ 8.10 (s, 1H), 8.02 (d, 1H), 7.73 (d, 1H), 7.53 (dd, 1H), 5.86 (dd, 1H), 3.89-3.85 (m, 1H), 3.73-3.69 (m, 1H), 2.43-2.31 (m, 1H), 2.06-1.92 (m, 2H), 1.80-1.64 (m, 1H), 1.60-150 (m, 2H).

Provenance & Evidence