Br[C:2]1[CH:3]=[C:4]([C:8]2([CH2:13][CH3:14])[O:12][CH2:11][CH2:10][O:9]2)[CH:5]=[CH:6][CH:7]=1.C([Li])CCC.CN([CH:23]=[O:24])C.[Cl-].[NH4+]>C1COCC1>[CH2:13]([C:8]1([C:4]2[CH:3]=[C:2]([CH:7]=[CH:6][CH:5]=2)[CH:23]=[O:24])[O:12][CH2:11][CH2:10][O:9]1)[CH3:14]17.8 g (70 mmol) of 2-(3-bromophenyl)-2-ethyl-[1,3]dioxolane are dissolved in 300 ml of THF and the mixture is cooled to −78° C. 34 ml (85 mmol) of a 2.5 M solution of butyllithium are added slowly, and the mixture is stirred for 30 minutes. 8.1 ml (105 mmol) of DMF are then added, and the mixture is brought back to 0° C., then treated with a saturated solution of ammonium chloride. After extraction with ethyl ether, the desired aldehyde is obtained in the form of yellow oil (m=14 g; Y=97%).
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