To a degassed solution of tert-butyl 3-(3-bromophenyl)propylcarbamate (57) (1.0 g, 3.1 mmol) and cyclopropyl acetylene (2.9 mL, 3.4 mmol, 70% soln in toluene) in diisopropylamine (4 mL) was added PdCl2(PPh3)2 (0.120 g, 0.17 mmol), tri-o-tolylphosphine (0.048 g, 0.16 mmol) and CuI (0.026 g, 0.16 mmol). The resulting mixture was degassed and stirred under nitrogen at 90° C. for overnight. The mixture was cooled to room temperature and concentrated under reduced pressure. The residue was partitioned between water and ethyl acetate. The organic layer was dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. Purification by flash chromatography (10-40% ethyl acetate-hexane gradient) gave tert-butyl 3-(3-(cyclopropylethynyl)phenyl)propylcarbamate. Yield (0.756 g, 79%). This alkyne was used for deprotection without futher purification.
