An environmentally benign protocol for the iodination of activated
aromatics, such as phenols, anilines, and hydroxycoumarins, using
inexpensive commercially available potassium iodide and ammonium
peroxodisulfate (1:2.5 molar equivalents per mole of substrate)
in aqueous methanol (MeOH-H2O, 6:1) at room
temperature has been developed. The protocol provides for ortho-selective monoiodination as the
predominant product without added acid and it is compatible with
a number of common oxidizible functional groups, such as formyl,
benzylic C-H, aromatic amines and hydroxymethyl. Good to
acceptable yields of monoiodinated products in acceptable reaction
times and exclusive ortho-iodination
for 7-hydroxycoumarins, despite the presence of vinylogous electron-rich
C3, are some of the key advantageous features of the method.
iodination - potassium iodide - ammonium peroxodisulfate - activated aromatics - coumarins
