3,4-DISUBSTITUTED FURANS .4. REGIOSPECIFIC CONVERSION OF 3,4-BIS(TRIMETHYLSILYL)FURAN TO 3,4-DISUBSTITUTED FURANS - A NOVEL SUZUKI-TYPE CROSS-COUPLING OF BOROXINES

A versatile building block is found in the easily s(trimethylsilyl)furan, which can be converted into boroxine 1 with BCl3 followed by aqueous workup. Subsequent Pd-catalyzed treatment with organic halides furnishes monoorganosilylfuran. Repetition of this reaction sequence affords 3,4-disubstituted furans, which are difficult to obtain by other methods. [GRAPHICS]