SyntheticPage 474
Published Dec 06, 2010
Triphenylphospine (6.25 g, 23.82 mmol, 2.05 eq.) was suspended in dry acetonitrile (20 ml) in a Schlenk and then cooled to 0°C using an ice-water bath. Bromine (1.2 ml, 3.71 g, 23.24 mmol, 2.00 eq.) was added dropwise using a syringe (after each drop the solution was allowed to return to colourless before the next drop was added). 2-Butyne-1,4-diol (1.00 g, 11.62 mmol, 1.00 eq.) was dissolved in dry acetonitrile (10 ml) and was slowly added to the reaction mixture (n.b. all solid triphenylphosphine is taken into solution at this point). The reaction was stirred overnight at ambient temperature under argon (n.b. as the reaction proceeds solid precipitates from the solution). The solvent was removed from the reaction mixture and the residue was taken up in diethylether (~150 ml). The solution was then filtered and the solvent was removed from the filtrate to leave the crude product as a yellow liquid. This crude product was purified by Kügelrohr distillation to give a clear liquid (bp 80°C under high vacuum). Purified yield = 1.64 g, 7.74 mmol, 67%.