Br[C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][C:11]=1[CH2:12][CH2:13][CH2:14][CH2:15][CH2:16][CH3:17])[C:8]([CH3:19])([CH3:18])[CH2:7][CH2:6][C:5]2([CH3:21])[CH3:20].C([Li])(C)(C)C.[C:27](=[O:29])=[O:28].Cl>O1CCCC1.CCCCC>[CH2:12]([C:11]1[C:2]([C:27]([OH:29])=[O:28])=[CH:3][C:4]2[C:5]([CH3:20])([CH3:21])[CH2:6][CH2:7][C:8]([CH3:19])([CH3:18])[C:9]=2[CH:10]=1)[CH2:13][CH2:14][CH2:15][CH2:16][CH3:17]15 g of 6-bromo-7-hexyl-1,1,4,4-tetramethyl-1, 2,3,4-tetrahydro-naphthalene were dissolved in 180 ml of tetrahydrofuran and treated dropwise at -78° C. with 64.5 ml of a 1.5 molar solution of tert.butyl-lithium in pentane. After stirring at -78° C. for 1 hour, a carbon dioxide stream was conducted vigorously into the reaction vessel for 2 hours. Subsequently, the reaction mixture was acidified by the addition of 190 ml of 2N hydrochloric acid, extracted several times with ethyl acetate, washed with water, dried over sodium sulfate and evaporated. The oily crude product was filtered over silica gel (eluent hexane, then hexane/ethyl acetate=4:1) and recrystallized from hexane. There were obtained 7.6 g of 3-hexyl-5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-naphthalen-2-yl-carboxylic acid in colorless crystals, m.p. 98°-99° C.
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