Reaction Steps
A mixture of amide 3c, 8.54 g, 22.4 mmol) and P2O5 (40 g) in o-dichlorobenzene (140 mL) was refluxed for overnight, then cooled to room temperature. It was cooled to 0° C. by application of an external ice-water bath. To this cooled mixture was cautiously added 200 mL of H2O. After the vigorous reaction had subsided, the dark solution was washed with toluene (2×40 mL). The aqueous layer was cooled to 0° C. and made to pH >11 with 50% aqueous NaOH. The resulting mixture was extracted with toluene (4×50 mL). The organic layers were dried (MgSO4), filtered. The filtrate was concentrated in vacuo. The residue was recrystallized from benzene, thereby affording a white solid (6.1 g, 79%). mp 146.5-147.4° C. 1H NMR (CDCl3) d 2.72 (s, 3 H, CH3), 7.38-7.51 (m, 4 H, aromatic) 7.61 (t, J=6.9 Hz, 1 H, aromatic), 7.75 (d, J=8.1 Hz, 1 H, aromatic), 7.84 (d, J=8.1 Hz, 1 H, aromatic), 7.94 (d, J=8.7 Hz, 1 H, aromatic). 13C NMR (CDCl3) d 24.34 (q, CH3), 94.58 (s, =CI--, aromatic), 118.20 (d, aromatic), 124.56 (s, aromatic), 126.31 (d, aromatic), 126.42 (d, aromatic), 126.94 (d, aromatic), 129.96 (d, aromatic), 131.68 (d, aromatic), 137.41 (d, aromatic), 137.51 (s, aromatic), 139.12 (s, aromatic), 150.88 (s, aromatic), 158.97 (s, =CCH3 --, aromatic). Anal. Calcd for C16H12IN: C, 55.67; H, 3.50; N, 4.06. Found: C, 55.63; H, 3.55; N, 4.07.
