C(sp³)–H functionalization of <i>N</i>-protected dialkylpyrrole derivatives with azodicarboxylates

A metal-free, catalytic route to the activation of C(sp³)-H bonds in <i>N</i>-protected dialkylpyrroles to diazodicarboxylates is reported using HB(C₆F₅)₂ as the optimized catalyst. These reactions tolerate aryl and alkyl substituents on the pyrrole <i>N</i>-atom as well as variation in the azodicarboxylates giving rise to 41 examples. These reactions were also performed on a gram scale and conversion to the corresponding amino-esters is demonstrated. A DFT computation study reveals that the Lewis acid adduct of azodicarboxylates generates a Lewis acidic <i>N</i>-atom capable of hydride abstraction from dimethylpyrrole, ultimately effecting C(sp³)-H functionalization.