C(#N)C.[Br:4][C:5]1[CH:6]=[C:7]([CH:12]=[C:13]([CH2:16][CH2:17][CH2:18][OH:19])[C:14]=1[CH3:15])[C:8]([O:10][CH3:11])=[O:9].S([O-])([O-])(=O)=O.[Na+].[Na+].[F:27][C:28]([F:36])(S(F)(=O)=O)C(O)=O>O>[Br:4][C:5]1[CH:6]=[C:7]([CH:12]=[C:13]([CH2:16][CH2:17][CH2:18][O:19][CH:28]([F:36])[F:27])[C:14]=1[CH3:15])[C:8]([O:10][CH3:11])=[O:9]
To an acetonitrile (0.6 M) suspension of methyl 3-bromo-5-(3-hydroxypropyl)-4-methylbenzoate (1 eq.) from the previous step and sodium sulfate (0.2 eq.) was added dropwise at 50° C. difluoro(fluorosulfonyl)acetic acid (1 eq.) over a period of 10 min. After the completion of addition, the reaction suspension was heated at 50° C. for another 16 h. The reaction mixture was then cooled to RT, poured into water and extracted with ether. The combined organic extracts were washed further with water and brine, 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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