3-Phenylfuran → 4,4,5,5-Tetramethyl-2-(4-phenyl-2-furanyl)-1,3,2-dioxaborolane

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Reaction Conditions

Reaction Steps

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.

Provenance & Evidence