Fe or Ni-catalyzed Decarboxylative C-C Couplings of Active Esters

Baran et al. have reported decarboxylative C-C bond forming reactions using previously prepared/isolated active esters from aliphatic carboxylic acids and phthalimide derivatives. According to their reports under catalytic systems such as iron(III) acetylacetonate / 1,2-bis(diphenylphosphino)benzene (L1) and nickel(II) chloride / 4,4'-di-tert-butyl-2,2'-bipyridine (L2), the decarboxylative C-C-coupling reaction of active esters with organozinc reagents successfully proceeds through single electron transfer. In these reactions, the alkyl-alkyl cross-coupling is accomplished by the use of alkylzinc reagents, and various functional groups like an active methylene group or ester group substituted reactants can be applied to this coupling. In this way, approaching the C-C-bond forming reaction from easily available carboxylic acids as starting materials has attracted attention as a halogen-free synthetic method.^{1, 2, 3)}