6-bromo-5-fluoro-2,3-dihydroinden-1-one

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 6-Bromo-5-fluoro-2,3-dihydro-1H-inden-1-one (commercially available), 4 g, 17.5 mmol), paraformaldehyde (2.48 g, 78.6 mmol) and N-methylanilinium trifluoroacetate (5.79 g, 26.2 mmol) were dissolved in anhydrous THF (80 mL) and refluxed overnight. The mixture was cooled to r.t. and concentrated. The residue was re-dissolved in EtOAc and brine. The phases were separated and the organic phase was dried over sodium sulfate and concentrated. The product was purified by flash column chromatography using heptane/EtOAc 7:1 as eluent affording the title compound (2.99 g, 71% yield). 1H NMR (400 MHz, CDCl3) δ ppm 3.73 (s, 3 H) 5.69 (m, 1 H) 6.39 (m, 1 H) 7.25 (s, 2 H) 8.10 (d, 1 H); MS (EI) m/z 240, 242 M+. refluxed overnight concentrated The residue was re-dissolved in EtOAc The phases were separated the organic phase was dried over sodium sulfate concentrated The product was purified by flash column chromatography