[OH:1][C:2]1[CH:3]=[C:4]([CH:7]=[CH:8][C:9]=1O)[CH:5]=[O:6].[CH2:11](Br)[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1.[C:19](=[O:22])([O-])[O-].[K+].[K+].CN(C)C=O>O>[CH2:11]([O:1][C:2]1[CH:3]=[C:4]([CH:7]=[CH:8][C:9]=1[O:22][CH2:19][C:2]1[CH:3]=[CH:4][CH:7]=[CH:8][CH:9]=1)[CH:5]=[O:6])[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1A mixture of 3,4-dihydroxybenzaldehyde (5.0 g), benzyl bromide (14.8 g), potassium carbonate (13 g) and N,N-dimethylformamide (120 ml) was stirred for two hours at 60° C. To the reaction mixture was added cold water (200 ml), which was subjected to extraction with ethyl acetate (150 ml). The organic layer was washed with a 5% aqueous solution of potassium hydrogencarbonate, which was washed with water and dried over anhydrous sodium sulfate. The solvent was distilled off to leave 3,4-dibenzyloxybenzaldehyde (10.5 g) as colorless crystals. m.p.: 87-88° C.
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