Acetic Anhydride → 1-Acetyl-2-methyl-4-(trifluoromethyl)-2,3-dihydro-1H-indole

Participants

Reaction Conditions

Reaction Steps

A mixture of 2-methyl-4-(trifluoromethyl)-1H-indole (Example 114D) (0.48 g, 2.41 mmol) was dissolved in HOAC (3.0 mL), cooled to 0° C. and NaBH3CN (0.454 g, 7.23 mmol) was added in one portion. After 5 min the mixture was removed from the cooling bath and stirred at rt for 14 h. The mixture cooled to 0° C. and the pH was adjusted to ca. 13 by addition of 1 N NaOH (20 mL) and further addition of solid NaOH pellets. The mixture was extracted with Et2O (×3), combined organics were washed (H2O, brine), dried over Na2SO4, filtered and concentrated in vacuo. The residue was dissolved in dry CH2Cl2 (10 mL) and treated with DMAP (0.884 g, 7.23 mmol). The mixture was cooled to 0° C. and Ac2O (0.455 mL, 4.81 mmol) was added dropwise via syringe. The mixture was stirred overnight, slowly warming to rt, diluted with CH2Cl2, washed (10% HCl, H2O, brine), dried over Na2SO4, filtered, and concentrated in vacuo. The residue was purified by flash chromatography (EtOAc/hexanes), affording 0.25 g of the title compound as a pale yellow oil: MS (ES) m/z 244 (M+1).

Provenance & Evidence