[N:1]([C:4]1[CH:9]=[CH:8][N:7]=[CH:6][C:5]=1[CH:10]=O)=[N+:2]=[N-:3].[Cl:12][C:13]1[CH:19]=[CH:18][CH:17]=[C:16]([Cl:20])[C:14]=1[NH2:15].C(N(CC)CC)C>C(Cl)Cl.[Ti](Cl)(Cl)(Cl)Cl>[N:1]([C:4]1[CH:9]=[CH:8][N:7]=[CH:6][C:5]=1/[CH:10]=[N:15]/[C:14]1[C:13]([Cl:12])=[CH:19][CH:18]=[CH:17][C:16]=1[Cl:20])=[N+:2]=[N-:3]Titanium tetrachloride (1M, 4.3 mL, 4.3 mmol) was added to a cooled (0° C.) mixture of 4-azidopyridine-3-carbaldehyde (1.06 g, 7.2 mmol), 2,6-dichloroaniline (1.17 g, 7.2 mmol) and triethylamine (3.0 mL, 21.6 mmol) in DCM (24 mL) under nitrogen. The resultant mixture was stirred for 3 hours at 0° C. before warming to room temperature and stirring for a further 3 hours. The reaction mixture was concentrated under reduced pressure. The residue was suspended in toluene and filtered though a pad of Celite®. The filtrate was concentrated to dryness under reduced pressure to afford the title compound as a yellow solid. This crude material was employed in the next step without further purification or analysis.
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