Arene C-H Iodination Using Aryl Iodides

Metathesis reactions represent powerful synthetic tools that have been used in a number of fields from the synthesis of natural product to functional material preparation. However, the C-H metathesis reaction is extremely rare. Herein, we report the first Pd(II)-catalyzed C-H iodination of arenes using 2-nitrophenyl iodides as the mild iodinating reagents via a formal metathesis reaction. Unusual C-I bond formation occurred with aryl iodides in preference to competing C-C coupling in this reaction. Assisted by aliphatic carboxyl directing groups, a range of hydrocinnamic acids and related arenes could be selectively iodinated at either meta- or ortho-positions of the phenyl ring. Remote diastereoselective C-H activation was also promising. This method might unfold a novel approach to iodinate challenging substrates. [GRAPHICS]