6-hydroxy-2-methyl-1-benzofuran-3-one

反応条件: temp:80.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

実験手順: To a stirred solution of resorcinol (5.5 g, 50 mmol) in methanesulfonic acid (75 mL) was added 2-bromopropionic acid (4.7 mL, 50 mmol) and P2O5 (4.0 g, 28 mmol). The resulting mixture was stirred for 30 min at 80° C. After cooling to room temperature, the reaction mixture was poured onto ice and extracted with chloroform (2×). The combined organic extracts were washed with brine, dried with sodium sulfate, and concentrated. The orange colored crude product (˜12 g) was carefully taken up into aqueous sodium hydroxide (2N, 245 mL) at 0-5° C., and the resulting mixture was stirred at room temperature overnight. The dark brown solution was cooled to 0° C., and carefully acidified to with concentrated HCI to pH ˜3. It was then extracted with ethyl acetate (3×). The combined organic extracts were washed with brine, dried with sodium sulfate, and concentrated. The crude material was purified on a silica gel column, eluting with ethyl acetate (20-75%) in hexanes. The final product was obtained as a crystalline solid upon standing at room temperature. The NMR showed a mixture of tautomers (mostly the enol form). After cooling to room temperature the reaction mixture was poured onto ice extracted with chloroform (2×) The combined organic extracts were washed with brine dried with sodium sulfate concentrated was carefully taken up into aqueous sodium hydroxide (2N, 245 mL) at 0-5° C. the resulting mixture was stirred at room temperature overnight The dark brown solution was cooled to 0° C. It was then extracted with ethyl acetate (3×) The combined organic extracts were washed with brine dried with sodium sulfate concentrated The crude material was purified on a silica gel column eluting with ethyl acetate (20-75%) in hexanes