Electronic Activation Enables the Borylation of Alkyl C–H Bonds in Saturated Nitrogen Heterocycles

Catalytic functionalization of C-H bonds is a valuable strategy for the synthesis and diversification of organic compounds. The catalytic borylation of heteroaromatic C-H bonds is well established, but the analogous borylation of alkyl C-H bonds in saturated heterocycles remains underdeveloped. Reactions with improved catalysts recently reported for the borylation of alkyl C-H bonds occurred with a narrow range of such nitrogen heterocycles. Here, we describe a broadly applicable approach to activate C-H bonds in saturated nitrogen heterocycles for iridium-catalyzed borylation by installing a group on nitrogen that increases the reactivity of specific C-H bonds. Mechanistic studies reveal that the electron withdrawing groups accelerate the rate of borylation by enhancing the energetics of multiple steps within the catalytic cycle.