[O:1]1[C:6]2[CH:7]=[CH:8][CH:9]=[CH:10][C:5]=2[CH:4]([CH2:11][CH2:12][OH:13])[CH2:3][CH2:2]1.C[N+]1([O-])CCOCC1>C(Cl)Cl.C(OCC)(=O)C.[Ru]([O-])(=O)(=O)=O.C([N+](CCC)(CCC)CCC)CC>[O:1]1[C:6]2[CH:7]=[CH:8][CH:9]=[CH:10][C:5]=2[CH:4]([CH2:11][CH:12]=[O:13])[CH2:3][CH2:2]1To a stirred solution of 2-(3,4-dihydro-2H-1-benzopyran-4-yl)ethanol (1.45 g, 8 mmol), N-methylmorpholine-N-oxide (1.41 g, 12 mmol) and 4 A molecular sieves (4.0 g) in methylene chloride (20 ml), tetrapropylammonium perruthenate (0.140 g, 0.4 mmol) was added. The reaction mixture was stirred at room temperature for 15 min., diluted with an equal volume of ethyl acetate (20 ml) and flash filtered through silica gel (eluant: methylene chloride/ethyl acetate 1:1). Concentration of the filtrate in vacuo afforded the title compound as an oily gum (0.92 g, 64%). NMR (300 MHz/CDCl3) 9.87 (1 H, s).
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