[C:1]1([CH:7]2[CH:16]=[CH:15][C:14]3[C:9](=[CH:10][CH:11]=[CH:12][CH:13]=3)[O:8]2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.B.C1C[O:21]CC1.[OH-].[Na+].OO>CCOCC.O>[C:1]1([C@@H:7]2[C@@H:16]([OH:21])[CH2:15][C:14]3[C:9](=[CH:10][CH:11]=[CH:12][CH:13]=3)[O:8]2)[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=1A solution of 2-phenyl-2H-chromene (2a) (167 mg, 0.8 mmol) and 1 molar BH3-THF (16 mL) was stirred for 2 h at 23° C. Solution was cooled to 0° C. before a 20% (w/w) aqueous solution of NaOH (4.8 mL) and 30% (w/w) aqueous solution of H2O2 (4.9 mL) were added. The reaction was slowly warmed to 23° C. and stirred for 12 h. The solution was then diluted with Et2O and H2O followed by acidification with 10% (w/w) aqueous HCl and extraction with Et2O. The organics were combined, dried over magnesium sulfate, filtered, and concentrated under reduced pressure. Purification by flash chromatography with 10% EtOAc/hexanes afforded 7 as a white solid (115 mg, 63%). Spectroscopic data was consistent with those previously reported.
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