Difluoro‐ and Trifluoromethylation of Electron‐Deficient Alkenes in an Electrochemical Microreactor

Abstract

Electrochemical microreactors, which have electrodes integrated into the flow path, can afford rapid and efficient electrochemical reactions without redox reagents due to the intrinsic properties of short diffusion distances. Taking advantage of electrochemical microreactors, Kolbe electrolysis of di-and trifluoroacetic acid in the presence of various electron-deficient alkenes was performed under constant current at continuous flow at room temperature. As a result, di-and trifluoromethylated compounds were effectively produced in either equal or higher yields than identical reactions under batch conditions previously reported by Uneyamas group. The strategy of using electrochemical microreactor technology is useful for an effective fluoromethylation of alkenes based on Kolbe electrolysis in significantly shortened reaction times.

Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance

“…Taking advantage of an intermolecular version of this conjunctive coupling, Wirth and co-workers reported a method for the “dimerizative” fluoroalkylation of Michael acceptors (Figure 2E) in flow reactors. 72 The analogous batch reaction was reported by Uneyama in 1988. 73 …”

Advances in electro- and sono-microreactors for chemical synthesis

“…In this case, H 2 SO 4 acted as an electrolyte between the electrodes and as the counter ion for diaryl iodonium hydrogen sulfates (intermediate). 39 Their yields of the Kolbe electrolysis reactions of di-and triuoroacetic acids in the presence of various electron-decient alkenes was comparable, and in some cases higher, than that of a batch reactor (batch: 11-45%, ow: 11-52%), 40 and in another work with the same reactor, the deprotection of an i Noc group from phenols and benzenethiol occurred in a rapid fassion. 41 Alternatively, the reactor can be made from polymers instead of aluminium, by using 3D printing additive manufacturing technology, allowing a reduction in the time and cost of construction as well as simplistic approach to customisation if required (Fig.…”

A Green Approach: Vicinal Oxidative Electrochemical Alkene Difunctionalization

“…In 1991, Kenji Uneyama reported an electrooxidation of trifluoroacetic acid in the presence of olefins, affording trifluoromethyl compounds. Additionally, Wirth and co‐workers have also developed a rapid and efficient way in which to allow the addition of CHF 2 and CF 3 radicals to various electron‐deficient alkenes, however via an electrochemical microreactor. The electrochemical microreactor developed by the group has a thin film flow channel of fluorinated ethylene propylene (FEP) embedded between two platinum sheets (Figure ).…”