[Si]([O:8][C:9]1[CH:10]=[CH:11][C:12]([CH3:23])=[C:13]([P:15](=[O:22])([O:19][CH2:20][CH3:21])[O:16][CH2:17][CH3:18])[CH:14]=1)(C(C)(C)C)(C)C.[F-].C([N+](CCCC)(CCCC)CCCC)CCC>C1COCC1.CCOC(C)=O>[OH:8][C:9]1[CH:10]=[CH:11][C:12]([CH3:23])=[C:13]([P:15](=[O:22])([O:16][CH2:17][CH3:18])[O:19][CH2:20][CH3:21])[CH:14]=1A mixture of diethyl 5-tert-butyldimethylsilyloxy-2-methylphenylphosphonate 1-3 (165 mg, 0.46 mmol) and 0.69 mL of a 1 M solution of tetrabutylammonium fluoride (0.69 mmol) in 4 mL of THF was stirred at rt for 1 h. The mixture was then diluted with EtOAc, washed with brine, dried (MgSO4) and evaporated. The resulting residue was subjected to MPLC on a 12 g column of SiO2 eluting with 35% EtOAc in hexanes (10 min) and then 50% EtOAc (10 min) to provide diethyl 5-hydroxy-2-methyl-phenylphosphonate 1-4 as an oil. 1H NMR (300 MHz, DMSO-d6): δ 1.23 (t, 6H, J=6 Hz), 2.36 (d, 3H, J=1 Hz), 3.9-4.0 (m, 4H), 6.87 (dd, 1H, J=8, 3 Hz), 7.12 (t, 1H, J=8 Hz), 7.20 (dd, 1H, J=14, 3 Hz), 9.55 (s, 1H).
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