Br[CH2:2]Br.[CH3:4][C:5]1([C:12]([OH:14])=[O:13])[CH2:10][CH2:9][C:8](=O)[CH2:7][CH2:6]1.[Cl-].[Na+]>C1COCC1.[Ti](Cl)(Cl)(Cl)Cl.[Zn]>[CH3:4][C:5]1([C:12]([OH:14])=[O:13])[CH2:10][CH2:9][C:8](=[CH2:2])[CH2:7][CH2:6]1
Under an argon stream, 3 ml of dibromomethane and 30 ml of titanium tetrachloride (methylene chloride 2M solution) were added to a solution of 7 g of zinc suspended in 200 ml of THF, under ice-cooling. The resultant solution was stirred for one hour. Then, a solution of 4.1 g of 1-methyl-4-oxo-1-cyclohexanecarboxylic acid (Example 26) in 40 ml of THF was added to the solution. The resultant solution was reacted for 12 hours. After reaction, 500 ml of an aqueous sodium chloride solution was added to the reaction solution. The solution was extracted three times with 100 ml of ethyl acetate. The organic layer obtained was washed three times with an aqueous solution of sodium chloride and dried over magnesium sulfate. The solvent was removed in vacuo. The oily substance formed was subjected to column chromatography using 20 g of silica gel. From the fraction eluted with hexane and ethyl acetate=2:1, the solvent was removed in vacuo, yielding 1.3 g of 1-methyl-4-methylene-1-cyclohexanecarboxylic acid as a colorless oil, which had the following physiochemical properties:
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