[CH2:1]([C:3]1[CH:4]=[C:5]([C:9](=[NH:14])[O:10][CH2:11][CH2:12][CH3:13])[CH:6]=[N:7][CH:8]=1)[CH3:2].[N:15]#[C:16]N>C(#N)C>[C:16]([N:14]=[C:9]([C:5]1[CH:6]=[N:7][CH:8]=[C:3]([CH2:1][CH3:2])[CH:4]=1)[O:10][CH2:11][CH2:12][CH3:13])#[N:15]The propyl 5-ethyl-3-pyridinecarboximidate were then dissolved in acetonitrile (5 ml), and an aqueous solution (30 ml) of cyanamide (1.13 g, 26.9 mmol), Na2HPO4 (1.29 g, 9.1 mmol) and NaH2PO4 ·2H2O (8.45 g, 54.2 mmol) was added to the solution. The mixture was stirred at room temperature for 19 hours. After reaction, the mixture was extracted with chloroform (50 ml×2). The chloroform layer was dried over anhydrous sodium sulfate, concentrated under reduced pressure and subjected to silica gel column chromatography (Wako Gel C-200, 50 g; eluted with hexane:ethyl acetate=5:1) to give 1.51 g (7.0 mmol) of propyl N-cyano-5-ethyl-3-pyridinecarboximidate (yield, 44%).
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