Whitby group

To a stirred solution of phenyl acetylene (5.10 mL, 46.42 mmol, 1.1 equiv.) in THF (60 mL) at -78 °C was added slowly dropwise n-butyl lithium (2.5 M in hexanes, 18.57 mL, 46.42 mmol, 1.1 equiv.).  The reaction mixture was warmed to -55 °C and HMPA (11.01 mL, 63.30 mmol, 1.5 equiv.) was added slowly dropwise.  The reaction was stirred at this temperature for 20 minutes before 5-bromopent-1-ene (5.00 mL, 42.20 mmol, 1 equiv.) in THF (20 mL) was added slowly dropwise.  The reaction was stirred for 16 hours.

The reaction was quenched with ammonium chloride solution (sat. aq., 30 mL) and the product was extracted into diethyl ether (3 x 50 mL).  The diethyl ether layers were combined and washed with water (3 x 50 mL) before being dried over magnesium sulphate, filtered and concentrated under reduced pressure.

The product was purified by column chromatography (silica gel, hexane) to yield the pure product as a colourless oil (5.81 g, 34.11 mmol, 73 %). 

Kobayashi, T.; Koga, Y.; Narasaka, K. J Organomet Chem 2001, 624, 73.