Diverse functionalization of strong alkyl C–H bonds by undirected borylation

Speeding up borylation Catalytic borylation is the rare reaction that can selectively target stronger over weaker saturated carbon–hydrogen (C–H) bonds. However, the trade-off has been that the reaction is slow and requires high excess of the hydrocarbon. Oeschger et al. now report that the right ligand (2-methylphenanthroline) coordinated to iridium can accelerate the reaction by 50- to 80-fold. This rate enhancement enables selective borylation of primary C–H bonds with the hydrocarbon as limiting reagent. The reaction is also unusually selective for β-C–H bonds in saturated heterocycles. Science , this issue p. 736