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 dichloromethane (101 mL). To this solution, 3,4-dihydro-2H-pyran (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 dichloromethane (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