[O:1]=[CH:2][C:3]1[CH:11]=[CH:10][C:8]([OH:9])=[C:5]([O:6][CH3:7])[CH:4]=1.[C:12]([O-])([O-])=O.[K+].[K+].[CH2:18](Br)[C:19]#C>CN(C=O)C>[CH3:12][O:9][C:8]1[CH:10]=[CH:11][C:3]([CH:2]=[O:1])=[CH:4][C:5]=1[O:6][CH2:7][C:18]#[CH:19]A mixture of vanillin 17 (0.76 g, 4.90 mmol), K2CO3 (1.37 g, 9.90 mmol) and propargyl bromide (1.19 g, 6.90 mmol) in DMF (30 mL) was refluxed at 80° C. for 1 hr. Reaction mixture was cooled to 0° C. in ice bath and filtered through a short bed of celite. Ethyl acetate (50 mL) was added and the mixture was washed with 1N HCl (20 mL), extracted with ethyl acetate (100 mL). The organic phase was combined and washed with brine and dried over anhydrous Na2SO4. After filtration, solvent was removed under reduced pressure and the crude residue was purified by flash chromatography (hexane/ethyl acetate: 8/2) to afford 18 as white solid (0.74 g, 80%). 1HNMR (400 MHz, CDCl3) δ 2.57 (t, 1H), 3.94 (s, 3H), 4.85-4.86 (d, J=2.44 Hz, 2H), 7.13-7.15 (d, J=8.16 Hz, 1H), 7.43-7.47 (m, 2H), 9.87 (s, 1H); 13CNMR (100 MHz, CDCl3) δ 56.06, 56.65, 109.58, 112.71, 126.21, 131.00, 150.11, 152.17, 190.85.
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