Electrochemical Cobalt-catalyzed Cyclotrimerization of Alkynes to 1,2,4-Substituted Arenes

The transition-metal-catalyzed [2 + 2 + 2] cyclotrimerization of alkynes is one of the most straightforward routes for constructing six-membered ring motifs. Although this strategy possesses high atom/step economy and readily available substrates, the catalyst cycling is the key problem. Herein, we disclosed a facile and efficient cobalt-catalyzed cyclotrimerization of alkynes through electrochemical tools. Both terminal and internal alkynes were tolerated under the mild reaction conditions, affording the 1,2,4-trisubstituted and hexasubstituted benzenes with high regioselectivity. Electrochemical redox accurately tuned the valence of Co species to cycle the catalyst smoothly during the whole reaction.

Automated summary

In this study, a facile and efficient cobalt-catalyzed cyclotrimerization of alkynes was disclosed using electrochemical tools. Both terminal and internal alkynes were tolerated under mild reaction conditions, producing products with high regioselectivity. The valence of Co species was accurately tuned through electrochemical redox to cycle the catalyst smoothly during the entire reaction process.