Copper-catalysed benzylic C-H coupling with alcohols via radical relay enabled by redox buffering

Cross-coupling reactions enable rapid, convergent synthesis of diverse molecules and provide the foundation for modern chemical synthesis. The most widely used methods employ sp(2)-hybridized coupling partners, such as aryl halides or related pre-functionalized substrates. Here, we demonstrate copper-catalysed oxidative cross-coupling of benzylic C-H bonds with alcohols to afford benzyl ethers, enabled by a redox buffering strategy that maintains the activity of the copper catalyst throughout the reaction. The reactions employ the C-H substrate as the limiting reagent and exhibit broad scope with respect to both coupling partners. This approach to direct site-selective functionalization of C(sp(3))-H bonds provides the basis for efficient three-dimensional diversification of organic molecules and should find widespread utility in organic synthesis, particularly for medicinal chemistry applications.