[OH:1][C:2]1[CH:3]=[C:4]([CH:7]=[CH:8][C:9]=1[OH:10])[CH:5]=[O:6].[CH:11]1(Br)[CH2:15][CH2:14][CH2:13][CH2:12]1.C(=O)([O-])[O-].[K+].[K+]>CN(C)C=O.C1(C)C=CC=CC=1>[CH:11]1([O:10][C:9]2[CH:8]=[CH:7][C:4]([CH:5]=[O:6])=[CH:3][C:2]=2[OH:1])[CH2:15][CH2:14][CH2:13][CH2:12]1A suspension of 3,4-dihydroxy benzaldehyde (50.0 g, 0.3623 mol), cyclopentyl bromide (135 g, 0.9058 mol) and potassium carbonate (50.0 g, 0.3623 mol) in N,N-dimethylformamide (500 mL) was stirred at about 75-80° C. for about 1.0 hr. 4×12.5 g potassium carbonate was then added after every 1.0 hr. The reaction mixture was cooled to ambient temperature and filtered to remove inorganic materials. The residue obtained after concentration of the filtrate was diluted with toluene (250 mL), and extracted with 5-10% aqueous sodium hydroxide solution (6×50 mL). The combined aqueous layer was acidified to pH about 3 to 5 by 5N aqueous hydrochloric acid solution. The solid which separated was filtered, washed with water and dried to give 4-cyclopentyloxy-3-hydroxy benzaldehyde.
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