Electricity-Driven, Three-Component Cascade Annulation Strategy with o‑Alkynylbenzaldehydes, o‑Phenylenediamines, and Diorganyl Diselenides: Sustainable Synthesis of 5‑(Organoselanyl)benzo[4,5]imidazo[2,1‑a]isoquinolines

We disclose a metal- and oxidant-free, highly atom-economic,
three-component
cascade annulation strategy starting from readily available starting
materials, i.e., o-alkynylbenzaldehydes, o-phenylenediamines, and diorganyl diselenides, for the
sustainable synthesis of highly functionalized and fused N-heteroaromatics, i.e., 5-(organoselanyl)benzo[4,5]imidazo[2,1-a]isoquinolines, via the concurrent formation of 4xCsp2-N and 1xCsp2-Se bonds under electrochemical conditions.
The transformation required electricity as the only green reagent,
which furnished the desired products in moderate to good yields along
with the formation of water and molecular hydrogen as innocuous byproducts,
demonstrating the high sustainability of the protocol.