Can. J. Chem. 69, 1326 (1991). A series of aryl bromides undergo a palladium-catalyzed coupling reaction with 3-[(tert-butyldimethylsilyl)oxymethyl]-4-(tri-n-butylstanny1)furan to provide 4-aryl-3-[(tert-butyldimethylsilyl)oxymethyl]furans in moderate to good yields. . Can. J. Chem. 69, 1326 (1991). Des rCactions de couplage, catalysCes par le palladium, entre divers bromures d'aryle et le oxymkthyll-3-(trimtthylstanny1)-4-furanne conduisent avec des rendements relativement faibles aux

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... tert-butyldimCthy1- silyl)oxymCthyl]-3-furannes. Mots clPs : palladium, couplage croisC, stannanes, furannes disubstitues en positions 3 et 4. [Traduit par la redaction] The preparation of 3,4-disubstituted furans is a formidable 6 OH ( 1 12.2 eq. n-BUU task since furan derivatives tend to lithiate (1) and add DME electrophiles (2) in the C-2 and C-5 positions. Elaborate THF S(t-Bu)k, (2) R+ + methods for the preparation of 3,4-disubstituted furans have 9 R=H therefore been developed to overcome these tendencies. Some R=s(t-su)Me, 2 of these include inter-(3) and intra-molecular (4) Diels-Alderretro-Diels-Alder sequences, synthesis of the furan ring from acyclic (5) and cyclic (6) precursors, and chemical modifications of commercially available 3,4-furandicarboxylic acid (7) . R$OH Nan. OMF We have recently described a simple preparation of 3,4-S(t-Bu)Me, disubstituted furans 1 (8) via a regiospecific C-4 lithiation of -"&OR2 2-(tert-butyldimethylsilyl)-3-(hydroxymethyl)furan 2 (Scheme 4 R=SnBu, 1 1). Quenching the dianion with electrophiles followed by a 5 R=SnMe, 6 R1=Sn~u" R2=si(t-Bu)Me2 carbon to oxygen silyl migration afforded 3,4-disubstituted n-Bu4NF 7 RRI.S~BU" RZ=H furans 1 in good yields. 8 R'=s~&" R~=s(~-Bu)M~,