Methyl 2-[(2,2-dimethyl-4,6-dioxo-[1,3]dioxan-5-ylidenemethyl)amino]-5-iodobenzoate → Methyl 6-iodo-4-oxo-1,4-dihydroquinoline-8-carboxylate

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Reaction Conditions

Reaction Steps

Compound 98 (3.00 g, 6.96 mmol) was added under argon to refluxing diphenylether (20 mL). The mixture was stirred at 250° C. for 45 min. After cooling to room temperature, the crude mixture was chromatographed (SiO2). Diphenylether was first eliminated by elution with dichloromethane and the desired product was recovered using elution by gradient (CH2Cl2→CH2C2/EtOH (95/5, v/v)) to give compound 99 (2.01 g, 6.11 mmol) as a green solid. Yield 88%; Rf (SiO2, CH2Cl2/EtOH, 95/5, v/v) 0.31; mp 75-77° C.; IR (KBr) ν 1213, 1271, 1303, 1491, 1560, 1577, 1628, 1701, 3100-3300 cm−1; 1H NMR (200 MHz, CDCl3) δ 4.02 (s, 3H), 6.36 (dd, 1H, J=1.4, 7.6 Hz), 7.72 (dd, 1H, J=6.0, 7.6 Hz), 8.59 (d, 1H, J=2.2 Hz), 8.92 (d, 1H, J=2.2 Hz), 11.61 (se, 1H); ESI-MS m/z 329.7 [M+H]+.

Provenance & Evidence