[NH2:1][C:2]1[C:7]([C:8]#[N:9])=[CH:6][CH:5]=[C:4]([CH:10]([O:13][CH3:14])[O:11][CH3:12])[N:3]=1.[CH:15](=O)[CH3:16].C(O[BH-](OC(=O)C)OC(=O)C)(=O)C.[Na+]>C(O)(=O)C>[C:8]([C:7]1[C:2]([NH:1][CH2:15][CH3:16])=[N:3][C:4]([CH:10]([O:13][CH3:14])[O:11][CH3:12])=[CH:5][CH:6]=1)#[N:9]2-Amino-3-cyano-6-dimethoxymethylpyridine (39.6 g, 0.2 mol) and 12 ml (0.2 mol) of acetaldehyde were dissolved in 400 ml of acetic acid, and the resulting solution was mixed with 45.5 g (0.2 mol) of sodium triacetoxyborohydride and stirred for 2.5 hours at room temperature. The reaction solution was concentrated under a reduced pressure, diluted with chloroform and then washed with 1 N sodium hydroxide aqueous solution. The organic layer was dried over anhydrous magnesium sulfate, magnesium sulfate was removed by filtration and then the filtrate was concentrated under a reduced pressure. Thereafter, the resulting residue was purified by silica gel column chromatography (hexane-ethyl acetate) to give 33.9 g of 3-cyano-2-ethylamino-6-dimethoxymethylpyridine as an oily material. The yield was 77%.
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