3,4-Dibromothiophene → 3-Bromo-4(trimethylsiloxypropynyl)thiophene

Participants

Reaction Conditions

Reaction Steps

Into a 250 mL 4 necked RB flask equipped with a magnetic stirring bar, thermometer, rubber septum, argon inlet and reflux condenser with argon outlet (tubed to a silicon oil bubbler) is added 48.3 g (229 mmol) of 3,4-dibromothiophene, 13.0 g of triethylamine, 20.1 g (157 mmol) of 3-trimethylsiloxypropyne, 130 mg of triphenylphosphine, 147 mg of copper iodide and 470 mg of dichlorobis(triphenylphosphine) palladium(II). The mixture is heated with a silicon oil bath to 70° C. under argon with stirring for 5.5 hrs. The cooled mixture is then concentrated on a rotary evaporator at reduced pressure and the residue taken up in 200 mL of hexanes and washed with 2×25 mL of water and the pentane phase dried over sodium sulfate and then concentrated on a rotary evaporator. The residue was chromatographed through neutral silica gel eluted with 2/1 methylene chloride/ethyl acetate to yield 8.9 g of 3-bromo-4(trimethylsiloxypropynyl)thiophene as a light yellow oil which was used directly to prepare 2-hydroxymethylselenolo[2,3-c]thiophene.

Provenance & Evidence