To a mixture of cyclopentyl(2S)-2-[(tert-butoxycarbonyl)amino]pent-4-ynoate (2.45 g, 8.72 mmol) and 4-iodo-bromobenzene (2.96 g, 10.46 mmol) in diethyl ether (4 ml) was added copper iodide (0.166 g, 0.872 mmol) and PdCl2(PPh3)2 (0.306 g, 0.436 mmol). Diethylamine (5.43 ml, 52.3 mmol) was then added and the mixture stirred at RT. After 2 hrs, LCMS showed complete reaction. The mixture was poured onto water and extracted with diethyl ether. The combined organic layers were washed with water and brine, dried over magnesium sulphate, filtered and evaporated in vacuo. The crude residue was subjected to column chromatography eluting with 5 to 10% EtOAc in hexanes. Yield=2.9 g, 6.51 mmol, 75% yield. LCMS purity 98%: m/z 437 [M+H]+.
