CV‐driven Optimization: Cobalt‐Catalyzed Electrochemical Expedient Oxychlorination of Alkenes via ORR

Abstract

Instead of screening reaction conditions by yield-based chemical trial-and-error, potential-based cyclic voltammetry was alternatively employed for optimization of electrochemical oxychlorination of alkenes. With this unconventional screening method, the catalyst system including catalysts, molar ratio of chloride sources and solvents were identified in a rational, time-and energy-efficient manner. The optimal catalytic system in combination with oxygen reduction reaction enabled broad substrate scopes for the desired transformation by taking advantages of persistent radical effect. UV-vis and CV titration experiments confirmed the in-situ formed catalytic species [CoCl 5 ]. Moreover, cyclic voltammetry was applied to obtain mechanistic insights in our reaction system.

Electrochemical Oxidative Difunctionalization of Alkenes to Access α-Oxygenated Ketones

“…On the other hand, air or O 2 is an ideal oxidant or oxygen source due to its safety, low cost, and sustainability. Using molecular oxygen as an oxygen source to construct oxygen-containing compounds under milder conditions is an important subject and a challenge . Based on our continuous efforts to study the radical multicomponent reactions and efficient green synthetic methods, herein, we demonstrated the dioxygenation of alkenes by the combination of organic electrochemistry and aerobic oxidation to obtain α-oxygenated ketones (Scheme d).…”

Designing Sites in Heterogeneous Catalysis: Are We Reaching Selectivities Competitive With Those of Homogeneous Catalysts?

“…In Figure two recent examples are provided where Ni-bpy complexes were used to help with the amination of aryl halides (Figure a) and with aryl-alkyl cross-couplings (Figure b) . Other organometallic electrocatalysts include Mn­(II) salts, used for the oxidative vicinal difunctionalization (diazidation, dichlorination, halotrifluoro­methylation) of alkenes, Pd acetate, employed for C–H activation, , Co acetate, to promote a [4+2] annulation of sulfonamides with alkynes, and Co chloride, for the oxychlorination of alkenes . The development of organometallic electrocatalysts for the electrocatalytic promotion of specific organic synthesis reactions selectively is still in its infancy, but much progress has been seen in recent years and more is expected in the near future.…”

“…Figure 42 two recent examples are provided where Ni-bpy complexes were used to help with the amination of aryl halides (Figure42a)561 and with aryl-alkyl cross-couplings (Figure42b) 562. Other organometallic electrocatalysts include Mn(II) salts, used for the oxidative vicinal difunctionalization (diazidation, dichlorination, halotrifluoromethylation) of alkenes,508 Pd acetate, employed for C−H activation,563,564 Co acetate, to promote a [4+2] annulation of sulfonamides with alkynes,565 and Co chloride, for the oxychlorination of alkenes 566. The development of organometallic electrocatalysts for the electrocatalytic promotion of specific organic synthesis reactions selectively is still in its infancy, but much progress has been seen in recent years and more is expected in the near future.In many of the examples cited above, either selectivity is not a critical issue or it is not dependent on the nature of the mediator.…”

Recent Progresses in the Preparation of Chlorinated Molecules: Electrocatalysis and Photoredox Catalysis in the Spotlight

“…When anodic and cathodic events are combined, the chloro-chalcogenation of alkenes is possible (Scheme 21). This was demonstrated by Chen, who reported a cobalt-catalyzed electrochemical oxychlorination of styrenes 77 to α-chloroacetophenones 78 [39]. To obtain reproducibility, reticulated vitreous carbon (RVC) electrodes were used.…”