[N:1]1([C:8]([O:10][C:11]([CH3:14])([CH3:13])[CH3:12])=[O:9])[CH2:7][CH2:6][CH2:5][NH:4][CH2:3][CH2:2]1.Br[C:16]1[CH:21]=[CH:20][C:19]([Br:22])=[CH:18][N:17]=1.C(=O)([O-])[O-].[K+].[K+]>CS(C)=O.C(OCC)(=O)C>[Br:22][C:19]1[CH:20]=[CH:21][C:16]([N:4]2[CH2:5][CH2:6][CH2:7][N:1]([C:8]([O:10][C:11]([CH3:14])([CH3:13])[CH3:12])=[O:9])[CH2:2][CH2:3]2)=[N:17][CH:18]=11.03 g (5 mmol) of 1,1-dimethylethyl 1,4-diazepane-1-carboxylate, 1.19 g (5 mmol) of 2,5-dibromopyridine and 0.7 g (5 mmol) of potassium carbonate suspended in 0.90 ml of dimethyl sulfoxide (DMSO) are introduced into an autoclave. The mixture is heated at 150° C. for 22 hours. The reaction mixture is allowed to cool to room temperature, it is taken up in ethyl acetate, and the organic solution is washed with water and then brine, and dried over sodium sulfate. The filtrate is concentrated under reduced pressure and the residue thus obtained is purified by chromatography on silica gel, eluting with a 99.5/0.5 mixture of dichloromethane and methanol. 1.63 g of product are obtained in the form of an oil, and are used without further purification in the following step.
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