[Cl:1][C:2]1[C:7]([Cl:8])=[C:6]([C:9](=[O:13])[CH2:10][CH2:11][CH3:12])[CH:5]=[CH:4][C:3]=1[OH:14].Br[C:16]1([C:20]([O:22]CC)=[O:21])[CH2:19][CH2:18][CH2:17]1.C(=O)([O-])[O-].[K+].[K+]>CN(C)C=O>[Cl:1][C:2]1[C:7]([Cl:8])=[C:6]([C:9](=[O:13])[CH2:10][CH2:11][CH3:12])[CH:5]=[CH:4][C:3]=1[O:14][C:16]1([C:20]([OH:22])=[O:21])[CH2:19][CH2:18][CH2:17]1A mixture of 2,3-dichloro-4-butyrylphenol (7 g, 0.03 mole), ethyl 1-bromocyclobutanecarboxylate (10.23 g, 0.049 mole) and potassium carbonate (7.5 g, 0.054 mole) in N,N-dimethylformamide (60 ml) was stirred and heated at 65° C. for 18 hours. The reaction mixture was poured into ice water and the resulting mixture was extracted with ether. The ether extract was washed with a 1% sodium hydroxide solution, then with water and finally dried over MgSO4. The ether was evaporated in vacuo and the residue treated with acetic acid (60 ml) and 5% hydrochloric acid (15 ml). The mixture was stirred and refluxed overnight. The solvents were evaporated in vacuo. The residue was chromatographed over a column containing silica gel (140 g) using methylene chloride/tetrahydrofuran/acetic acid 50/1/1 as the eluent. The pertinent fractions were united, treated with toluene and evaporated in vacuo to obtain 1-(2,3-dichloro-4-butyrylphenoxy)cyclobutane-1-carboxylic acid as a liquid whose identity was confirmed by NMR and purity by thin layer chromatography.
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