3-Iodopyridine → 3-{[4-(Difluoromethoxy)phenyl]ethynyl}pyridine

Participants

Reaction Steps

A solution of 3-iodopyridine (205 mg, 1.0 mg) in triethylamine was treated with tetrakis(triphenylphosphine)palladium (80 mg, 0.069 mmol), copper iodide (18 mg, 0.097 mmol) and a solution of 1-(difluoromethoxy)-4-ethynylbenzene (168 mg, 1.0 mmol) in acetonitrile at room temperature, heated at 60° C. for 1 h, cooled and concentrated to dryness to afford 3-{[4-(difluoromethoxy)phenyl]ethynyl}pyridine as a residue. The residue (240 mg) was dissolved in acetone, treated sequentially with a solution of NaHCO3 (50 mg) and MgSO4 (180 mg) in H2O and KMnO4 (327 mg), stirred for 10 minutes at room temperature and extracted with 1/1 Et2O/hexane. The combined extracts were concentrated to dryness to give 1-[4-(difluoromethoxy)phenyl]-2-pyridin-3-ylethane-1,2-dione. A mixture of 1-[4-(difluoromethoxy)phenyl]-2-pyridin-3-ylethane-1,2-dione (230 mg), N-methylguanidine hydrochloride (155 mg) and Na2CO3 (240 mg) in ethanol was heated at reflux temperature for 1.5 h. and concentrated in vacuo. The resultant residue was purified by chromatography (silica gel, EtOAc/2.0 M NH3 in EtOH: 97/3) to give the title compound (130 mg) as a solid, mp: 173-175° C., identified by NMR and mass spectral analyses. MS (+) APPI: 333 (M+H)+.

Provenance & Evidence