Cl.[F:2][C:3]1[C:12]([F:13])=[C:11]2[C:6]([CH2:7][CH2:8][CH2:9][O:10]2)=[C:5]([I:14])[C:4]=1[O:15]COC>C1COCC1.CC(OC)(C)C>[F:2][C:3]1[C:12]([F:13])=[C:11]2[C:6]([CH2:7][CH2:8][CH2:9][O:10]2)=[C:5]([I:14])[C:4]=1[OH:15]10.4 ml of conc. HCl are added to a solution of 20.2 g (56.7 mmol) of 7,8-difluoro-5-iodo-6-methoxymethoxychroman in 100 ml of THF, and the mixture is stirred at 20° C. for 18 h. The batch is diluted with MTBE, and the solution is washed with water. The aqueous phase is extracted with MTBE, and the combined organic phases are washed with water and sat. sodium chloride soln. The solution is dried using sodium sulfate and concentrated to dryness. The crude product is purified by column chromatography (SiO2, n-heptane:MTBE=1:1), giving 7,8-difluoro-5-iodochroman-6-ol as a pale-brown solid.
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