[CH2:1]([C:3]1([CH2:16][CH3:17])[CH2:8][CH:7](O)[C:6]2[CH:10]=[C:11]([C:14]#[N:15])[CH:12]=[CH:13][C:5]=2[O:4]1)[CH3:2].O.C1(C)C=CC(S(O)(=O)=O)=CC=1.O>C1(C)C=CC=CC=1.C(OCC)(=O)C>[CH2:16]([C:3]1([CH2:1][CH3:2])[CH:8]=[CH:7][C:6]2[CH:10]=[C:11]([C:14]#[N:15])[CH:12]=[CH:13][C:5]=2[O:4]1)[CH3:17]A mixture of 2,2-diethyl-3,4-dihydro-4-hydroxy-2H-1-benzopyran-6-carbonitrile (2.28 g) and p-toluenesulfonic acid hydrate (0.19 g) in toluene was refluxed for an hour and 20 minutes with azeotropic removal of the formed water. The reaction mixture was diluted with ethyl acetate, and then washed with water and brine successively. The extract was dried over anhydrous magnesium sulfate and evaporated in vacuo. The residue was purified with silica gel column chromatography using a mixture of methylene chloride and n-hexane (1:5) as an eluent to give 2,2-diethyl-2H-1-benzopyran-6-carbonitrile (1.47 g).
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