[CH2:1]([C:4]1([C:10]2[CH:15]=[CH:14][CH:13]=[CH:12][CH:11]=2)[CH2:9][CH2:8][CH2:7][CH2:6][O:5]1)[CH:2]=C.C[N+]1([O-])CC[O:20]CC1.I([O-])(=O)(=O)=O.[Na+].CCOC(C)=O>C1COCC1.O.CO.O=[Os](=O)(=O)=O>[C:10]1([C:4]2([CH2:1][CH:2]=[O:20])[CH2:9][CH2:8][CH2:7][CH2:6][O:5]2)[CH:15]=[CH:14][CH:13]=[CH:12][CH:11]=1
To a solution of 2-allyl-2-phenyltetrahydro-2H-pyran (370 mg, 1.829 mmol, Int. 10B) in THF (2.5 mL) was added a solution of N-methylmorpholine-N-oxide (321 mg, 2.74 mmol) in water (2.5 mL), and then 0.37 mL of 2.5% OsO4 in water was also added. The mixture was stirred at room temperature for 1 day. The reaction was quenched with aq Na2S2O3 and the product was extracted with EtOAc. The extract was washed with brine, and the combined aqueous layers were back extracted with EtOAc once and combined. The extracts were dried over Na2SO4 and evaporated to give an oily residue. The residue was dissolved in MeOH (5 mL). A solution of sodium periodate (469 mg, 2.195 mmol) in water (5 mL) was added dropwise at 0° C. As soon as the addition started, white precipitate formed. The mixture was stirred for 30 mins at the same temperature and poured into EtOAc. The extract was washed with brine, and the combined aqueous layers were back extracted with EtOAc and combined. The extracts were dried over Na2SO4 and evaporated to give an oily residue. The residue was purified by Combiflash (40 g silica gel) eluting with 1:9 EtOAc-hexane to give 2-(2-phenyltetrahydro-2H-pyran-2-yl)acetaldehyde as an oil (239 mg). 1H NMR (400 MHz, CDCl3) δ ppm 9.64-9.68 (1 H, m), 7.36-7.46 (4 H, m), 7.25-7.31 (1 H, m), 3.74-3.81 (1 H, m), 3.55-3.64 (1 H, m), 2.58-2.75 (2 H, m), 2.29-2.39 (1 H, m), 1.80-1.92 (1 H, m), 1.59-1.75 (2 H, m), 1.40-1.58 (2 H, m).
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