[Na].CO[CH:4](OC)[C:5](=[CH:8]O)[C:6]#[N:7].[C:12]([CH2:14][C:15](=[S:17])[NH2:16])#[N:13].[OH-].C([N+](C)(C)C)C1C=CC=CC=1>Cl.C(N(CC)CC)C>[C:12]([C:14]1[C:15]([SH:17])=[N:16][CH:4]=[C:5]([C:6]#[N:7])[CH:8]=1)#[N:13]A suspension of the sodium salt of 2-dimethoxymethyl-3-hydroxy-acrylonitrile (3.94 g, 23.86 mmol) in hydrochloric acid (20 ml, 0.5 M) is heated at 50° C. for 30 minutes. Excess hydrochloric acid is neturalized using triethylamine, before adding cyanoacetothioamide (2.39 g, 23.9 mmol) and a catalytic amound of benzyltrimethylammonium hydroxide. The mixture is stirred at room temperature for two hours, heated at 60° C. for 2 hours and then refluxed for 4 hours. Evaporation of the solvents leaves a solid that is purified on silicagel to yield 3,5-dicyano-2-marcaptopyridine.
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