Hydrochloric Acid → 2-(4-Hydroxy-phenyl)benzofuran-5-OL

関与物質

反応手順

A solution of 3-Fluoro anisole (2 g, 16 mmol) and 2,5-dimethoxyphenacetyl chloride in dichloroethane (50 mL) was treated with AlCl3 (2.3 g, 18 mmol) and stirred at rt until TLC analysis indicated reaction was complete. The reaction was worked up by adding a 2 N HCl aq solution to the reaction (slowly) and washing with saturated NaHCO3 aq, brine and drying over MgSO4. After filtering, the EtOAc was concentrated and chromatographed on silica gel (EtOAc/hexanes 1:4) to yield 1 gram of the acylated intermediate 76 as well as an isomer as an oily solid that was used as is for the next reaction step. All of 76 from the previous step (1 g, 3.3 mmol) was heated with pyr-HCl at 180° C.-200° C. until TLC indicated reaction completion. The reaction was worked up by partitioning between 2 N HCl aq and EtOAc and washing the EtOAc with saturated NaHCO3, brine, and drying over MgSO4. The solution was filtered, concentrated and chromatographed on silica gel to yield 0.48 g of impure pdt 77. The product thus obtained was recrystallized from EtOAc/hexanes to yield desired product plus a small amt of unidentified impurity: Mp=218-222° C.; 1H NMR (DMSO-d6) δ 10.39 (s, 1 H), 9.20 (s, 1 H), 7.74 (t, 1 H, J=8.7 Hz), 7.37 (d, 1 H, J=8.8 Hz), 6.96-6.94 (m, 2 H), 6.79-6.70 (m, 3 H); MS 243 (M−H)−.

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