Polar π stacking for metal-free near, remote, and ultra-remote C–H coupling with aryliodanes

Abstract

We introduce a C–H coupling process in which an aromatic C–I position serves as trampoline for targeting various aromatic C–H positions. The reaction is set in motion by an interaction between the λ3-iodane ArI(OAc)2 and the π system of polyunsaturated organosilanes. In particular, the silyl-terminated enynes engage in fully regioselective ortho and para C–H functionalization, with selectivity switch achieved by reversing the order of the substrate’s ene and yne fragments. Density functional theory (DFT) calculations show that the ortho selectivity is governed by a [3,3] sigmatropic rearrangement, while the para coupling occurs through a directional three-point π interaction of the enyne-derived cationic π system, giving rise to an essentially barrierless [5,5] sigmatropic rearrangement. Furthermore, iodane-guided C–H functionalization of 2-iodonaphthalene could be directed to the ultra-remote C6 position through further π extension of the organosilanes partner. The latter reaction represents a nearly unprecedented example of a formal [7,7] sigmatropic rearrangement.