Hunsdiecker-Type Bromodecarboxylation of Carboxylic Acids with Iodosobenzene Diacetate–Bromine

Carboxylic acids are bromodecarboxylated in moderate to good yields on reaction with iodosobenzene diacetate and bromine under irradiation with a tungsten lamp. The reaction works very well with carboxylic acids having a primary, secondary or tertiary α-carbon atom, although diphenylacetic acid gives benzophenone. Benzoic acid derivatives are bromodecarboxylated in moderate yields if electron-withdrawing substituents are present in the benzene ring, while they are recovered mostly unchanged if the substituents are electron-donating. Partially iodinated products have been isolated in low yield from the bis-bromodecarboxylation of dicarboxylic acids having two bridgehead α-carbon atoms.