Reversing conventional site-selectivity in C(sp3)–H bond activation

One of the core barriers to developing C–H activation reactions is the ability to distinguish between multiple C–H bonds that are nearly identical in terms of electronic properties and bond strengths. Through recognition of distance and molecular geometry, remote C(sp2)–H bonds have been selectively activated in the presence of proximate ones. Yet achieving such unconventional site selectivity with C(sp3)–H bonds remains a paramount challenge. Here we report a combination of a simple pyruvic acid-derived directing group and a 2-pyridone ligand that enables the preferential activation of the distal γ-C(sp3)–H bond over the proximate β-C(sp3)–H bonds for a wide range of alcohol-derived substrates. A competition experiment between the five- and six-membered cyclopalladation step, as well as kinetic experiments, demonstrate the feasibility of using geometric strain to reverse the conventional site selectivity in C(sp3)–H activation