1-(3,5-Diamino-6-chloropyrazinoyl-2-methyl-pseudothiourea hydroiodide (0.2 g, 0.51 mmol) was added to a suspension of 27 in a mixture of THF (35 mL) and triethylamine (3 mL). The reaction mixture was stirred at reflux for 3 h, then the supernatant was separated and the solvent was removed under reduced pressure. The brown residue was washed with ether (2×30 mL) followed by addition of 10% HCl (5 mL). The solid material was collected, dissolved in methanol and precipitated by addition of ethyl acetate. The precipitate was washed with 10% HCl and dried to give compound 28 (131 mg, 51%) as a beige solid. 1H NMR (300 MHz, DMSO-d6) δ 1.52 (br s, 4H), 2.42 (m, 2H), 3.31 (m, 2H), 6.43 (m, 1H), 6.61 (m, 2H), 7.42 (br s, 2H), 7.90 (br s, 1H), 8.82 (br s, 1H), 8.98 (br s, 1H), 9.25 (s, 1H) 10.52 (s, 1H). APCI MS m/z=394 [C16H20ClN7O3+H]+.
