[CH2:1]([O:3][C:4](=[O:12])[C:5]1[CH:10]=[CH:9][CH:8]=[C:7]([OH:11])[CH:6]=1)[CH3:2].[CH3:13][C:14](=[CH2:16])[CH3:15].OS(C(F)(F)F)(=O)=O.CCN(CC)CC>C(Cl)Cl>[CH2:1]([O:3][C:4](=[O:12])[C:5]1[CH:10]=[CH:9][CH:8]=[C:7]([O:11][C:14]([CH3:16])([CH3:15])[CH3:13])[CH:6]=1)[CH3:2]Into a solution of 3-hydroxy-benzoic acid ethyl ester (10.14 g, 0.061 mol) in CH2Cl2 (200 mL) cooled to −78° C. was condensed isobutylene (150 mL) followed by addition of triflic acid (1.08 mL, 0.061 mol). The reaction mixture was allowed to warm to −20° C. When a solution was obtained and tlc indicated loss of starting material, the reaction was quenched with Et3N (6.8 mL, 0.049 mol) and left to warm to ambient temperature. The solution was concentrated and the residue chromatographed on an ISCO combiflash eluting with 0-10% EtoAc/hexane to give 12.91 g (95%) of the title compound.
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