Hydrochloric Acid → 6-Bromo-3,3,7-trimethylindolin-2-one

Participants

Reaction Conditions

Reaction Steps

A mixture of N′-(3-bromo-2-methylphenyl)isobutyrohydrazide (1.14 g, 4.23 mmol) and CaH (0.356 g, 8.46 mmol) in 1,2,3,4-tetrahydronaphthalene (10 mL) was heated to 200° C., and stirred at 200° C. for 17 h. The mixture was cooled to 0° C. and to the mixture was added water (1.63 mL) and MeOH (1.63 mL) slowly. At 0° C. the PH of the mixture was adjusted to PH1 by adding conc. HCl. The mixture then was heated to reflux for 1 h. The reaction mixture was cooled to rt, and NaOH (3N) was added to the mixture, adjusting to pH 5. The resultant mixture was diluted with EtOAc, washed with water and brine, dried and concentrated. Purification of the residue by flash chromatography over silica gel, using 30% EtOAc in hexane, gave 6-bromo-3,3,7-trimethylindolin-2-one. 1H-NMR (DMSO-d6) δ 10.58 (1H, s), 7.21 (1H, d, J=8.0 Hz), 7.07 (1H, d, J=8.0 Hz), 2.27 (3H, s), 1.24 (6H, s). Mass Spectrum (ESI) m/e=254.0 (M+1).

Provenance & Evidence