Dimethylformamide → 2,3-Dichloroisonicotinaldehyde

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[Cl:1][C:2]1[C:7]([Cl:8])=[CH:6][CH:5]=[CH:4][N:3]=1.C([Li])CCC.CN([CH:17]=[O:18])C>C1COCC1>[Cl:1][C:2]1[C:7]([Cl:8])=[C:6]([CH:17]=[O:18])[CH:5]=[CH:4][N:3]=1

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온도: -78 °C

실험 절차

To a solution of 2,3-dichloropyridine (10 g, 67.57 mmol) [C.A.S. 2402-77-9] in dry THF (200 ml) cooled at −78° C. under a nitrogen atmosphere, n-butyllithium (37.165 ml, 74 mmol, 2 M in hexanes) was dropwise added. The resulting reaction mixture was stirred at −78° C. for 20 min. Then dry DMF (6.28 ml, 81.087 mmol) was added dropwise. After 15 min stirring at −78° C., the mixture was allowed to warm to room temperature, quenched with water and extracted with DCM. The combined organic extracts were dried (Na2SO4) and evaporated in vacuo. The crude residue was purified by short open column chromatography (DCM as eluent). The desired product fractions were collected and evaporated in vacuo to give a residue that was further purified by column chromatography (silica gel; DCM/heptane up to 50% as eluent). The desired fractions were collected and evaporated in vacuo to yield intermediate compound D41 (4.15 g, 34.9%) as a white solid.