Br[C:2]1[CH:7]=[CH:6][C:5]([F:8])=[CH:4][N:3]=1.[NH:9]1[CH2:14][CH2:13][NH:12][CH2:11][CH2:10]1>>[F:8][C:5]1[CH:6]=[CH:7][C:2]([N:9]2[CH2:14][CH2:13][NH:12][CH2:11][CH2:10]2)=[N:3][CH:4]=1With stirring, 500 mg (2.84 mmol) of 2-bromo-5-fluoropyridine and 1.22 g (14.2 mmol) of piperazine are heated at 150° C. for 24 h. After cooling, excess piperazine is distilled off in vacuo (Kugelrohr, 1.5 mbar, 120° C.). The residue is purified by flash chromatography (dichloromethane/ethanol/conc. ammonia solution, 30:1:0.1).
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