[C:1]([C:3]([O:5][CH2:6][CH3:7])=[O:4])#[N:2].C1(N=[CH:15][C:16]2[O:17][CH:18]=[CH:19][C:20]=2[CH3:21])C=CC=CC=1.ClC(OCC)=O>C1(C)C(C)=CC=CC=1>[CH2:6]([O:5][C:3]([C:1]1[CH:21]=[C:20]2[CH:19]=[CH:18][O:17][C:16]2=[CH:15][N:2]=1)=[O:4])[CH3:7]Ethyl cyanoformate(21.4 g, 0.216 mol) and 3-methylfuran-2-carbaldehyde-N-phenylimine(10.0 g, 54.1 mmol) were mixed at room temperature in xylene (50 mL) then heated to reflux at 120 to 140° C. with stirring. A xylene (30 mL) solution of 11.7 g (0.108 mol) of ethyl chloroformate was added dropwise for an hour to the resulting mixture. After all the solution had been added, the reaction mixture was heated to reflux for 2 hours, it was allowed to cool to room temperature, and the solvent was distilled off to give 14.0 g of crude product. This product was purified by column chromatography on silica gel, giving 5.40 g (52.3% yield) of 5-ethoxycarbonylfuro[2,3-c]pyridine.
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