CC(C)([O-])C.[K+].[O:7]=[C:8]1[C:16]2[C:11](=[N:12][C:13]([CH:17]=O)=[CH:14][CH:15]=2)[CH2:10][O:9]1.[NH4+].[Cl-].C1[CH2:25][O:24][CH2:23]C1>CC(O)(C)C>[CH3:23][O:24]/[CH:25]=[CH:17]/[C:13]1[N:12]=[C:11]2[CH2:10][O:9][C:8](=[O:7])[C:16]2=[CH:15][CH:14]=1.[CH3:23][O:24]/[CH:25]=[CH:17]\[C:13]1[N:12]=[C:11]2[CH2:10][O:9][C:8](=[O:7])[C:16]2=[CH:15][CH:14]=1To a suspension of (methoxymethyl)triphenylphosphorium chloride (889 mg, 2.6 mmol) in anhydrous THF (10 mL) is added slowly to a solution of potassium tert butoxide in tBuOH (2.4 mL of a 1.0 M solution in tBuOH, 2.4 mmol) under an argon atmosphere. The brown reaction mixture is stirred at room temperature for 30 min, cooled to 0° C. and treated with 5-oxo-5,7-dihydro-furo[3,4-b]pyridine-2-carbaldehyde (326 mg, 2.0 mmol) in one portion. The dark brown reaction mixture is stirred at room temperature for 3 h and then poured into saturated aqueous NH4Cl solution (30 mL). The reaction mixture is extracted with EtOAc (2×). The combined organic extracts are dried Na2SO4, filtered and concentrated. The residue is purified by chromatography (silica gel, EtOAc/hexane) to give the higher Rf E-isomer, E-2-(2-Methoxy-vinyl)-7H-furo[3,4-b]pyridin-5-one (111 mg, 0.58 mmol) and lower Rf Z-isomer, Z-2-(2-Methoxy-vinyl)-7H-furo[3,4-b]pyridin-5-one (61 mg, 0.32 mmol). Total yield is 45%.
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