[Br:1][C:2]1[CH:3]=[C:4]([CH:9]=[C:10]([CH2:13][CH2:14][CH2:15][O:16][CH:17]([F:19])[F:18])[C:11]=1[CH3:12])[C:5](OC)=[O:6].CC(C[AlH]CC(C)C)C.CC(OI1(OC(C)=O)(OC(C)=O)OC(=O)C2C=CC=CC1=2)=O.C(=O)(O)[O-].[Na+]>ClCCl.CCOCC>[Br:1][C:2]1[CH:3]=[C:4]([CH:9]=[C:10]([CH2:13][CH2:14][CH2:15][O:16][CH:17]([F:18])[F:19])[C:11]=1[CH3:12])[CH:5]=[O:6]To a dichloromethane (0.07 M) solution of methyl 3-bromo-5-[3-(difluoromethoxy)propyl]-4-methylbenzoate (1 eq.) from the previous step was added DIBAL-H (1.5 M solution in toluene, 2.2 eq.). The resulting solution was stirred at RT for 1.5 h and then carefully quenched with 10% aq. HCl. The aqueous layer was separated and back-extracted with ether. The combined organic extracts were washed further with brine, dried over Na2SO4, filtered and the filtrate concentrated in vacuo. The crude alcohol thus obtained was taken up again in dichloromethane (0.07 M) and then added Dess-Martin periodinane (1.0 eq.) and sodium bicarbonate (1.2 eq.). After stirring at RT for 40 min, the reaction mixture was diluted with ether and washed sequentially with sat. aq. NaHSO3, 1 N aq. NaOH, water and brine. The organic extract was dried over Na2SO4, filtered and the filtrate concentrated in vacuo. Purification of the crude product by way of flash chromatography (SiO2, Hex→1:1 (v/v) Hex:EtOAc) afforded the title compound as a colorless oil.
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