[Cl:1][C:2]1[N:3]=[N:4][C:5]([Cl:12])=[CH:6][C:7]=1[Si:8]([CH3:11])([CH3:10])[CH3:9].[NH2:13][NH2:14].C1COCC1.C(N(CC)C(C)C)(C)C>>[Cl:12][C:5]1[N:4]=[N:3][C:2]([NH:13][NH2:14])=[C:7]([Si:8]([CH3:11])([CH3:10])[CH3:9])[CH:6]=1.[Cl:1][C:2]1[N:3]=[N:4][C:5]([NH:13][NH2:14])=[CH:6][C:7]=1[Si:8]([CH3:11])([CH3:10])[CH3:9]To a solution of 3,6-dichloro-4-(trimethylsilyl)pyridazine (9.67 g, 43.7 mmol) (Turck et al., J. Heterocycl. Chem., 1990, 27, 1377; prepared using the method described by Trécourt et al., J. Heterocycl. Chem., 1995, 32, 1057) in a 1.0 M solution of hydrazine in THF (131 ml, 131 mmol) was added N,N-diisopropylethylamine (7.5 ml, 43.8 mmol) and the mixture was stirred at reflux under nitrogen for 68 h. The mixture was allowed to cool, silica gel was added and the solvent was evaporated in vacuo. The residue was then purified by flash chromatography (silica gel, 5% MeOH/CH2Cl2) to give 1.24 g (13%) of 6-chloro-3-hydrazino-4-(trimethylsilyl)pyridazine and 6.34 g (67%) of the title compound as a yellow-brown solid; 1H NMR (360 MHz, CDCl3) δ 0.39 (9H, s), 3.96 (2H, br s), 6.24 (1H, br s), 7.08 (1H, s).
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