反应详情

温度

-40 °C

A solution of n-BuLi (6.2 mL, 2.5 M solution in hexane) was added drop-wise to a solution of 3-phenylfuran (1.5 g, 10.40 mmol) in dry tetrahydrofuran (100 mL) at −78° C. under nitrogen. It was warmed slowly to −40° C. over 45 min and stirred at this temperature for another 30 min. The mixture was cooled again to −78° C. followed by the dropwise addition of 4,4,5,5-tetramethyl-2-(propan-2-yloxy)-1,3,2-dioxaborolane (3.72 g, 19.99 mmol). After warming to room temperature, the mixture was quenched with NH4Cl (aq) and extracted with ethyl acetate (3×80 mL). The combined organic layers were dried over anhydrous sodium sulfate, filtered and concentrated in vacuo to give the residue, which was precipitated by cooling to afford 4,4,5,5-tetramethyl-2-(3-phenylfuran-2-yl)-1,3,2-dioxaborone as a white solid (400 mg, 14.0%). The mother liquid was purified by silica gel column chromatography eluting with 2% ethyl acetate in petroleum ether to afford 4,4,5,5-tetramethyl-2-(4-phenylfuran-2-yl)-1,3,2-dioxaborolane (200 mg, crude), which was used to the next step without further purification.

1. temperatureThe mixture was cooled again to −78° C.
2. temperatureAfter warming to room temperature
3. customthe mixture was quenched with NH4Cl (aq)
4. extractionextracted with ethyl acetate (3×80 mL)
5. dry with materialThe combined organic layers were dried over anhydrous sodium sulfate
6. filtrationfiltered
7. concentrationconcentrated in vacuo
8. customto give the residue, which
9. customwas precipitated
10. temperatureby cooling
11. customto afford 4,4,5,5-tetramethyl-2-(3-phenylfuran-2-yl)-1,3,2-dioxaborone as a white solid (400 mg, 14.0%)
12. customThe mother liquid was purified by silica gel column chromatography
13. washeluting with 2% ethyl acetate in petroleum ether