[S-]C#N.[NH4+].Br.C(N1CCC(=O)C(Br)C1)(=[O:8])C.C([N:20]1[CH2:25][CH2:24][C:23](=O)[CH:22]([S:27][C:28]#[N:29])[CH2:21]1)(=O)C.Cl>O>[NH:29]1[C:23]2[CH2:24][CH2:25][NH:20][CH2:21][C:22]=2[S:27][C:28]1=[O:8]Ammonium thiocyanate (5.54 g, 72.8 mmol) was mixed with water (450 ml) and heated to 80°. A solution of N-acetyl-3-bromo-4-piperidone hydrobromide (20.0 g, 66.2 mmol) in water (200 ml) was added dropwise over 3 hours. The reaction was then allowed to stir at 80° for sixteen hours. The reaction solution (containing the crude N-acetyl-3-thiocyanato-4-piperidone) was treated with concentrated hydrochloric acid (6 ml of a 12M solution, 93 mmol) and heated to reflux for 2 hours. The reaction mixture was then freeze-dried, and the residue dissolved in methanol and filtered. The precipitate was purified by column chromatography (eluant: 89:10:1 chloroform:methanol: concentrated ammonium hydroxide) to provide the title product as a white solid, m.p. 208° (decomp.) (0.60 g, 3.8 mmol, 6% yield).
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