Oxidative coupling of furan derivatives to bifurans catalyzed by palladium(II)

Furan and its 2-substituted derivatives (substituents: –CH₃, –CHO, –COOCH₃, –COOC₂H₅, –CH(OOCCH₃)₂) have been shown to react with palladium acetate in solution at 90–130°C giving the corresponding bifuran derivatives in high yields. The following order of activities has been obtained: –H, –CH₃, –CHO>–COOCH₃, –COOC₂H₅, –CH(OOCCH₃)₂>–COOH, which corresponds to the substituent effect in electrophilic substitution in heteroaromatic compounds.

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, 2- (: –CH₃, –CHO, –COOCH₃, –COOC₂H₅, –CH(OOCCH₃)₂) 90–130° . : –H, –CH₃, –CHO>–COOCH₃, –COOC₂H₅, –CH(OOCCH₃)₂>–COOH, .