p-Toluenesulfonic acid → 5-bromo-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole-3-carbaldehyde

Participants

Reaction Steps

p-Toluenesulfonic acid (10 mg, 0.052 mmol) was added to a solution of 5-bromo-indazole-3-carbaldehyde (100 mg, 0.444 mmol) and 3,4-dihydro-2H-pyran (75 mg, 0.891 mmol) in a mixture of THF/CH2Cl2 (1:1, 6 mL). The reaction mixture was stirred for 12 h at room temperature after which the solvent was removed in vacuo. The residue was dissolved in CH2Cl2 (20 mL) and poured in water (20 mL). The organic layer was separated, and the aqueous layer was extracted with CH2Cl2 (20 mL). The combined organic layers were washed with water (40 mL) and brine (40 mL), dried over Na2SO4 and concentrated. Purification by flash chromatography (CH2Cl2) afforded 110 mg, (80% yield) of the title compound as a solid. 1H NMR (400 MHz, CDCl3): δ 10.21 (s, 1H), 8.47 (s, 1H), 7.56 (m, 2H), 5.80 (dd, 1H, J=3.2 and 9.2 Hz), 3.98 (m, 1H), 3.79-3.74 (m, 1H), 2.57-2.49 (m, 1H), 2.20-2.12 (m, 2H), 1.83-1.57 (m, 3H).

Provenance & Evidence