[CH2:1]([O:3][C:4](=[O:25])/[C:5](/[O:22][CH2:23][CH3:24])=[CH:6]/[C:7]1[CH:12]=[CH:11][C:10]([O:13]CC2C=CC=CC=2)=[CH:9][C:8]=1[CH3:21])[CH3:2].B(F)(F)F.O(CC)CC.CSC>ClCCl>[CH2:1]([O:3][C:4](=[O:25])/[C:5](/[O:22][CH2:23][CH3:24])=[CH:6]/[C:7]1[CH:12]=[CH:11][C:10]([OH:13])=[CH:9][C:8]=1[CH3:21])[CH3:2]To a solution of (Z)-3-(4-benzyloxy-2-methyl-phenyl)-2-ethoxy-acrylic acid ethyl ester (46.1 g, 135.4 mmol) in dichloromethane (500 ml) was added BF3-OEt2 (186 ml, 677 mmol, 46%) and dimethyl sulfide (149 ml, 2.03 mol). The reaction mixture was stirred at ambient temperature for 14 h, poured onto ice water and extracted two times with dichloromethane. The combined extracts were washed with ice water/brine 1/1 and dried over sodium sulfate. The solvent was removed under reduced pressure and the residue purified by column chromatography (silica gel, n-heptane/AcOEt) to give 23.1 g (92.3 mmol, 68% over three steps) of the title compound as yellow crystals.
Wird geladen…
