[F:1][C:2]1[CH:7]=[C:6]([F:8])[CH:5]=[CH:4][C:3]=1I.[C:10]([OH:14])(=[O:13])[C:11]#[CH:12].C(NC(C)C)(C)C>CN(C=O)C.Cl[Pd](Cl)([P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)[P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1>[F:1][C:2]1[CH:7]=[C:6]([F:8])[CH:5]=[CH:4][C:3]=1[C:12]#[C:11][C:10]([OH:14])=[O:13]4.95 ml (41.4 mmol) of 2,4-difluoroiodobenzene and 2.56 ml (41.4 mmol) of propiolic acid were dissolved in DMF (16 ml). Following cooling of the reaction medium to 0° C. (ice-water bath), 578 mg (0.83 mmol) of Pd(PPh3)2Cl2 and 308 mg (1.66 mmol) of Cul were added. The reaction solution was then cooled to −10° C. (ice methanol bath) and 14.5 ml (103.4 mmol) of diisopropylamine were added dropwise at this temperature. The cooling bath was then removed and the reaction mixture was stirred a further 16 h after RT had been re-established. The reaction solution was then diluted with EA and washed successively with a 2N HCl solution and a satd aq. NaCl solution. Following drying over MgSO4, filtration, and removal of solvent in vacuo, the residue was boiled with hexane and filtered after cooling to RT. The residue was dissolved in diethyl ether at 30° C. and filtered at this temperature. By removal of solvent in vacuo there were obtained from the filtrate 6.43 g (35.3 mmol, 85%) of (2,4-difluorophenyl)propiolic acid.
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