Hydrochloric Acid → 3,6-Difluorocarbazole

Participants

Reaction Conditions

Reaction Steps

A reaction tube was charged with sodium tert-butoxide (7.218 g, 75.1 mmol), 2-chloro-4-fluoro-N-(4-fluorophenyl)aniline (3.600 g, 15.0 mmol), tri-tert-butylphosphonium tetrafluoroborate (0.305 g, 1.1 mmol), palladium diacetate (0.169 g, 0.8 mmol), and anhydrous 1,4-dioxane (80 mL). The tube was sealed under nitrogen and heated in an oil bath at 110° C. for 20 hrs. After cooling to room temperature, the mixture was treated with 2M aqueous hydrochloric acid (90 mL) and extracted with methylene chloride (3×50 mL). The combined organic layers were washed with saturated aqueous sodium chloride, dried (anhydrous sodium sulfate), and concentrated in vacuo. The residue was purified by silica gel chromatography (20-50% methylene chloride/hexanes). The solids were rinsed with hexanes and dried to afford pure compound as a white powder (1.1 g, 36%). 1H NMR (300 MHz, CDCl3) δ 7.99 (br s, 1H), 7.67 (dd, 2H, J=8.7, 2.4 Hz), 7.36 (dd, 2H, J=8.7, 4.2 Hz), 7.19 (td, 2H, J=9.0, 2.4 Hz).

Provenance & Evidence