Palladium-Catalyzed C-H Iodination of Arenes by Means of Sulfinyl Directing Groups.

C-H iodination of aromatic compounds has been accomplished with the aid of sulfinyl directing groups under palladium catalysis. The reaction proceeds selectively at the  peri -position of polycyclic aryl sulfoxides or at the  ortho -position of phenyl sulfoxides. The iodination products can be further converted via iterative catalytic cross-coupling at the expense of the C-I and C-S bonds. Computational studies suggest that  peri -C-H palladation would proceed via a non-directed pathway, wherein neither of the sulfur nor oxygen atom of the sulfinyl group coordinates to the palladium before and at the transition state.