Thionyl Chloride → 3,5-Diiodobenzonitrile

To a stirred solution of 3,5-diiodbenzoic acid (1.7 g, 4.5 mmol) in dichloromethane (DCM; 10 mL) was added oxalyl chloride (2.9 g, 23 mmol). After 5 hours, the volatile contents were removed under reduced pressure. The resulting residue was poured with caution into cold ammonium hydroxide (50 mL, 28%) and stirred for 2 h. The amide product was removed by filtration and the collected residue was dissolved in DCM and washed with 1 M HCl, 1 M NaOH, water and brine. The organic layer was dried with MgSO4. Removal of DCM in vacuo afforded 3,5-diiodobenzamide which was used without further purification. Thionyl chloride (8.2 g, 69 mmol) was added to the collected amide and the mixture was heated under reflux for 18 h. The reaction mixture was allowed to cool and excess thionyl chloride removed under reduced pressure. The resulting residue was dissolved in EtOAc and washed with a saturated solution of NaHCO3 (3×10 mL), water (2×10 mL), brine and dried over anhydrous MgSO4. Concentration of the organic solution followed by column chromatography purification yielded the titled compound as an off white solid in 60% yield; mp 129-131° C.; 1H-NMR (300 MHz, CDCl3) δ (ppm): δ 8.30 (t, J=1.4 Hz, 1H), 7.94 (d, J=1.5 Hz, 2H). 13C-NMR (75 MHz, CDCl3) δ (ppm): 149.7, 139.6, 115.6, 115.5, 94.5 HRMS (m/z): [M+H]+ calc. for C7H4I2N, 355.8428. found 355.8439.