58138-79-7

4774-14-5

58138-79-7

General procedure for the synthesis of 2,6-diiodopyrazine from 2,6-dichloropyrazine: 2,6-dichloropyrazine (2.5 g, 16.8 mmol, 1.0 eq.), p-toluenesulfonic acid (6.4 g, 33.6 mmol, 2.0 eq.), sodium iodide (20.0 g, 133.3 mmol, 8.0 eq.), 15-crown-5 (2.0 mL), and cyclobutanesulfone (40 mL) were mixed in a sealed tube and the reaction was heated at 150 °C for 2 hours. After completion of the reaction, the mixture was cooled to room temperature and water (100 mL) was added to the reaction mixture. The reaction mixture was neutralized with saturated sodium bicarbonate solution and subsequently washed with saturated sodium thiosulfate solution. The mixture was extracted with ether (5 x 100 mL), the ether extracts were combined, dried with anhydrous sodium sulfate and concentrated under reduced pressure. Water (10 mL) was added to the concentrate to precipitate 2,6-diiodopyrazine, the solid was collected by filtration, washed sequentially with water and pentane, and freeze-dried to give a light yellow powdery product (2.1 g, 38% yield). The product was characterized by 1H NMR (400 MHz, CDCl3): δ 8.74 (s, 2H); mass spectrum (M+H)+ = 332, retention time (Rt) = 1.29 min.