Electrochemical Site-selective Alkylation of Tropones via Formal C(sp3)-C(sp2) Coupling Reaction.

The first site-selective electrochemical alkylation of tropones is realized by reacting 2-acetoxytropones and redox-active-esters (RAEs). The electroreductive protocol enables the preparation of mono- and disubstituted tropones in high yields (up to 71%) under very mild conditions. Dedicated voltammetric measurements served for the identification of 2-acetoxytropones as a class of valuable trapping agents of nucleophilic radical species and shed light on the whole mechanistic profile. Wide tolerance towards functional groups (27 examples) and application to late-stage functionalization of a bioactive compound (i.e. Colchicine analogue), emphasize the synthetic impact of the present methodology.