[OH:1][C:2]1[C:11]2[C:10]([CH3:13])([CH3:12])[CH2:9][CH2:8][C:7]([CH3:15])([CH3:14])[C:6]=2[CH:5]=[C:4]([CH:16]=[O:17])[CH:3]=1.[H-].[Na+].[CH2:20]([O:22][CH2:23][CH2:24]Br)[CH3:21]>CN(C=O)C>[CH3:13][C:10]1([CH3:12])[CH2:9][CH2:8][C:7]([CH3:15])([CH3:14])[C:6]2[CH:5]=[C:4]([CH:16]=[O:17])[CH:3]=[C:2]([O:1][CH2:21][CH2:20][O:22][CH2:23][CH3:24])[C:11]1=236 g (156 mmol) of 4-hydroxy-5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalene-2-carbaldehyde are dissolved in 400 mL of anhydrous DMF. 6.5 g (163 mmol) of 60% sodium hydride are added portionwise and the reaction medium is stirred for 1 hour. 25 g (163 mmol) of 2-ethoxyethyl bromide are added portionwise and the medium is stirred at room temperature for 2 hours and then hydrolysed and extracted with ethyl ether. The organic phase is washed with 1N sodium hydroxide solution, and then three times with water. The residue obtained is purified by chromatography (eluent:heptane). A yellow oil is obtained (m=40.7 g; yield=86%).
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