[Br:1][C:2]1[CH:15]=[CH:14][C:5]([CH2:6][CH:7]([C:10](=O)[CH2:11][CH3:12])[C:8]#[N:9])=[CH:4][CH:3]=1.O.[NH2:17][NH2:18].C(O)C.C(O)(=O)C>C(OCC)(=O)C.[OH-].[Na+]>[Br:1][C:2]1[CH:3]=[CH:4][C:5]([CH2:6][C:7]2[C:10]([CH2:11][CH3:12])=[N:18][NH:17][C:8]=2[NH2:9])=[CH:14][CH:15]=1
A mixture of 2-(4-bromo-benzyl)-3-oxo-pentanenitrile (1, 10.4 g, 39.1 mmol) and hydrazine hydrate (1.9 ml, 39.1 mmol) in 35 ml of a 1:1 mixture of ethanol and acetic acid was heated in a microwave reactor to 140° C. for 15 min. After cooling the reaction mixture was diluted with ethyl acetate and washed several times with sat. sodium bicarbonate, followed by brine. The organic layer was dried over Na2 SO4 and evaporated to give a mixture of 2 and its N-acetamide. For conversion of the latter to 2, the crude product was taken up in 1N sodium hydroxide and heated to 160° C. in a microwave reactor until no N-acetamide could be detected by LC-MS (10-20 min). The reaction mixture was extracted with ethyl acetate, the organic layer was washed with brine, dried over Na2 SO4 and evaporated to yield 2 as a white powder, which was used in the next step without further purification.
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