Formaldehyde → 6-bromo-2-methylene-2,3-dihydro-1H-inden-1-one

Participants

Reaction Steps

A solution of 6-bromo-2,3-dihydro-1H-inden-1-one (0.3 g, 1.36 mmol), paraformaldehyde (0.4 g, 13.6 mmol), phenylboronic acid (0.2 g, 1.64 mmol) and trifluoroacetic acid (0.1 mL, 0.15 g, 1.36 mmol) in dry toluene (10 mL) was refluxed for 5 hours. When starting material was totally consumed, the crude mixture was cooled to room temperature, neutralized with saturated aqueous Na2CO3, extracted with ethyl acetate, dried and concentrated under reduced pressure. The residue was purified by flash column chromatography (silica gel, petroleum ether-ethyl acetate, 95:5) to give compound 6-bromo-2-methylene-2,3-dihydro-1H-inden-1-one (89 mg, 30%) as a white solid. 1H NMR (CDCl3, 400 MHz): 3.71 (s, 2H), 5.68 (s, 1H), 6.39 (s, 1H), 7.38-7.40 (d, 1H), 7.70-7.72 (d, 1H), 7.99 (s, 1H).

Provenance & Evidence