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In a 3-necked round-bottom connected to a Dean-Stark trap, a solution of 2-amino-5-iodopyridine (Preparation 1, 500 mg) and diethyl ethoxymethylenemalonate (0.92 mL) is heated at 130° C. for 2 h. The reaction is cooled to room temperature. Diphenyl ether (5 mL) is added and the reaction is heated at 250° C. for 1 h. Upon cooling the mixture to room temperature, a solid precipitates and is filtered and washed with hexanes. The crude solid is adsorbed onto silica and chromatographed eluting with CH2Cl2 (2 L). Product-containing fractions are combined and concentrated to afford a solid. The crude product is recrystallized from CH2Cl2/hexanes to yield 251 mg (32%) of the title compound as a yellow solid. Physical characteristics: m.p. 166-168° C.; 1H NMR (300 MHz, DMSO-d6) δ 9.24, 8.85, 8.38, 7.62, 4.27, 1.30; IR (drift) 1747, 1611, 1558, 1506, 1473, 1355, 1345, 1291, 1266, 1258, 1152, 1140, 1118, 840, 796 cm−1; MS (ESI+) m/z 345; Anal. found: C, 38.37; H, 2.48; N, 8.11.

1. temperaturethe reaction is heated at 250° C. for 1 h
2. temperatureUpon cooling the mixture to room temperature
3. customa solid precipitates
4. filtrationis filtered
5. washwashed with hexanes
6. customchromatographed
7. washeluting with CH2Cl2 (2 L)
8. concentrationconcentrated
9. customto afford a solid
10. customThe crude product is recrystallized from CH2Cl2/hexanes