The synthesis was performed following a procedure of Stara, Irena G.; Stary, Ivo; Kollarovic, Adrian; Teply, Filip; Saman, David; Fiedler, Pavel. Coupling reactions of halobenzenes with alkynes. The synthesis of phenylacetylenes and symmetrical or unsymmetrical 1,2-diphenylacetylenes. Collect. Czech. Chem. Commun. (1999), 64(4), 649-672. A solution of 4.45 g (12.5 mmol) of (4-Iodo-phenyl)-methyl-carbamic acid tert-butyl ester in 25 ml piperidine was degassed (argon) and treated with 722 mg (0.625 mmol) Pd(PPh3)4 and 119 mg (0.625 mmol) Cul. The reaction mixture was stirred at 45° C. for 10 min and then slowly (45 min) heated to 80° C. while adding 0.9 ml (9.4 mmol) of 4-pentin-1-ol. At 80° C. a second portion of 0.9 ml (9.4 mmol) 4-pentin-1-ol was added during 45 min. The reaction mixture was stirred at this temperature for 2 h and then extracted with chilled water acidified with KHSO4/Et2O (3×). The organic phases were washed with aqueous 10% NaCl, dried (Na2SO4) and evaporated. Purification by flash-chromatography on silica gel (CH2Cl2/EtOAc 95:5) yielded 3.15 g (87%) of [4-(5-Hydroxy-pent-1-ynyl)-phenyl]-methyl-carbamic acid tert-butyl ester, mp: 103-105° C.; MS: 289 (M).
