Synthesis of 4-alkyl-3-bromo-2(5H)-furanones and unsymmetrically disubstituted 3,4-dialkyl-2(5H)-furanones by palladium-catalyzed cross-coupling reactions

Easily available 3,4-dibromo-2(5H)-furanone undergoes a regioselective cross-coupling reaction with alkylboronic acids in the presence of catalytic amounts of PdCl2(MeCN)2 and AsPh3 and a large molar excess of Ag2O to provide the corresponding 4-alkyl-3-bromo-2(5H)-furanones in satisfactory yields. These monobromo derivatives have proven to be useful precursors to unsymmetrically substituted 3,4-dialkyl-2(5H)-furanones which include the racemic form of naturally occurring seiridin.