Br[C@H:2]1[C@H:7]([OH:8])[C:6]2[CH:9]=[C:10]([C:13]#[N:14])[CH:11]=[CH:12][C:5]=2[O:4][C:3]1([CH2:17][CH3:18])[CH2:15][CH3:16].C(=O)([O-])[O-].[K+].[K+].O>CN(C)C=O>[O:8]1[CH:7]2[CH:2]1[C:3]([CH2:17][CH3:18])([CH2:15][CH3:16])[O:4][C:5]1[CH:12]=[CH:11][C:10]([C:13]#[N:14])=[CH:9][C:6]=12A mixture of trans-3-bromo-2,2-diethyl-3,4-dihydro-4-hydroxy-2H-1-benzopyran-6-carbonitrile (1.95 g) and potassium carbonate (1.74 g) in N,N-dimethylformamide (8 ml) was stirred overnight at ambient temperature. The reaction mixture was poured into water, extracted with ethyl acetate, and then washed with water and brine successively. The extract was dried over anhydrous magnesium sulfate, treated with active charcoal, and evaporated in vacuo. The residue was purified with silica gel column chromatography using a mixture of methylene chloride and n-hexane (1:2) as an eluent to give 3,4-epoxy-2,2-diethyl-3,4-dihydro-2H-1-benzopyran-6-carbonitrile (1.17 g).
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