[O:1]1[C:10]2[CH:9]=[CH:8][CH:7]=[C:6]([OH:11])[C:5]=2[CH2:4][CH2:3][CH2:2]1.Br[CH2:13][C:14]([O:16][CH3:17])=[O:15].C(=O)([O-])[O-].[Cs+].[Cs+].C(O)C(N)(CO)CO>C(#N)C>[CH3:17][O:16][C:14](=[O:15])[CH2:13][O:11][C:6]1[CH:7]=[CH:8][CH:9]=[C:10]2[C:5]=1[CH2:4][CH2:3][CH2:2][O:1]2A solution of chroman-5-ol (2.1 g, 14 mmol), methyl bromoacetate (1.6 mL, 16.8 mmol), and cesium carbonate (6.8 g, 21 mmol) in 50 mL acetonitrile was heated at 60° C. for 3 hours. PS-Trisamine scavenger resin was then added to the warmed solution followed by an additional 30 minutes heating. The reaction mixture was then cooled and filtered. The filtrate was collected, diluted with 100 mL ether, washed with brine (1×50 mL), dried (Na2SO4), and the solvent removed in vacuo to give 2.1 g (68%) of the title compound, pure enough for subsequent use. 400 MHz 1H NMR (DMSO-d6) δ 6.92 (t, 1H, J=8.3 Hz), 6.33 (d, 1H, J=8.3 Hz), 6.31 (d, 1H, J=8.3 Hz), 4.72 (s, 2H), 4.02 (t, 2H, J=5.1 Hz), 3.64 (s, 3H), 2.56 (t, 2H, J=6.6 Hz), 1.83 (m, 2H).
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