C([C:3]1[CH:12]=[C:11]2[C:6]([C:7](=[O:13])CC[O:10]2)=[CH:5][CH:4]=1)=C.C[N+]1([O-])[CH2:20][CH2:19][O:18][CH2:17][CH2:16]1.[OH2:22]>C1COCC1.ClCCl.[Os](=O)(=O)(=O)=O.O>[OH:22][CH:12]([C:3]1[CH:20]=[C:19]2[C:6]([C:7](=[O:13])[CH2:16][CH2:17][O:18]2)=[CH:5][CH:4]=1)[CH2:11][OH:10]To a mixture of 7-vinylchroman-4-one (Preparation 2D, 0.801 g, 4.60 mmol) and a 50% solution of NMO in water (0.953 mL, 4.60 mmol) in THF (11 mL) at room temperature was added a 4% aqueous solution of osmium tetroxide in water (1.44 mL, 0.184 mmol). The reaction mixture was stirred at room temperature overnight. The reaction mixture was diluted with dichloromethane (200 mL) and washed with water (40 mL). The organic layer was collected and was washed with brine (40 mL). The combined aqueous layers were extracted with dichloromethane (200 mL), and the combined organic layers were dried over anhydrous sodium sulfate. Concentration under reduced pressure afforded 7-(1,2-dihydroxyethyl)chroman-4-one (0.950 g, 4.56 mmol, 99% yield) as a dark yellow oil. The product had an HPLC ret. time=0.587 min.−Column: Chromolith SpeedROD 4.6×50 mm (4 min.); Solvent A=10% MeOH, 90% H2O, 0.1% TFA; Solvent B=90% MeOH, 10% H2O, 0.1% TFA. LC/MS M+1=209.0.
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