[CH2:1]([C:3]1([CH2:15][CH3:16])[CH:8]=[CH:7][C:6]2[CH:9]=[C:10]([C:13]#[N:14])[CH:11]=[CH:12][C:5]=2[O:4]1)[CH3:2].C(=O)(O)[O-:18].[Na+].ClC1C=CC=C(C(OO)=O)C=1>ClCCl>[CH2:15]([C:3]1([CH2:1][CH3:2])[CH:8]2[O:18][CH:7]2[C:6]2[CH:9]=[C:10]([C:13]#[N:14])[CH:11]=[CH:12][C:5]=2[O:4]1)[CH3:16]12 g of the above chromene are dissolved in 400 ml of abs. dichloromethane, the obtained solution is mixed with anhydrous sodium bicarbonate and oxidized during 3 days with 31 mg of m-chloroperbenzoic acid. The slightly yellow suspension is partitioned between an aq. ammoniumhydroxide solution (5%) and dichlormethane, the organic phases are washed with water and dried over sodiumsulphate. The oil, obtained after concentration, is purified by flash-chromatography (silica gel/dichloromethane, hexane 2:3). Besides of educt, 2,2-diethyl-3,4-epoxy-3,4-dihydro-2H-1-benzopyran-6-carbonitrile is obtained as colorless oil.
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