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

Participants

Reaction Steps

p-Toluenesulfonic acid (30 mg, 0.158 mmol) was added to a solution of 5-nitro-indazole-3-carbaldehyde (300 mg, 1.569 mmol) and 3,4-dihydro-2H-pyran (265 mg, 3.150 mmol) in a mixture of THF/CH2Cl2 (1:1, 8 mL). The reaction mixture was stirred for 12 h at room temperature and then the solvent was removed in vacuo. The residue was taken in CH2Cl2 (50 mL) and poured in water (20 mL). The organic layer was separated, the aqueous layer was extracted with CH2Cl2 (50 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 title compound 215 mg (50% yield) as a solid. 1H NMR (400 MHz, CDCl3): δ 10.23 (s, 1H), 9.23 (d, 1H, J=2.0 Hz), 8.35 (dd, 1H, J=2.0 and 9.2 Hz), 7.80 (d, 1H, J=9.2 Hz), 5.89 (dd, 1H, J=2.8 and 8.8 Hz), 3.98 (m, 1H), 3.80 (m, 1H), 2.53 (m, 1H), 2.19 (m, 2H), 1.76 (m, 3H).

Provenance & Evidence