Aluminum(III) Chloride → 1-Methyl-1H-indazol-5-ol

Participants

Reaction Steps

To a solution of (2t) (0.99 g, 6.1 mmol) in toluene (30 mL) was added AlCl3 (2.44 g, 18.3 mmol) at room temperature, upon which a purple colored mixture formed. After refluxing for 20 minutes, an olive colored mixture formed. The mixture was refluxed for 2 hours, allowed to cool to room temperature and poured into an ice-water bath. The insoluble solids were collected by filtration (398 mg). The filtrate was extracted with DCM, filtered through 1PS paper, evaporated in vacuo and purified on the Biotage eluting with (1:9) then (3:7) Et2O/DCM and finally (1:1) DCM/Et2O. The product fractions were evaporated in vacuo affording compound (3t) as a brown foam (122 mg). Total combined yield, 520 mg (58%). 1H NMR (400 MHz, CDCl3) 7.38 (d, J=7.8 Hz, 1H), 7.17 (dd, J=7.8, 1.6 Hz, 1H), 7.13 (d, J=1.6 Hz, 1H), 5.19-5.18 (m, 1H), 4.51-4.44 (m, 1H), 4.43-4.36 (m, 1H), 2.53-2.45 (m, 1H), 2.36-2.30 (m, 1H); MS (ESI+) m/z 149 (M+H) detected.

Provenance & Evidence