Abstract:An unprecedented γ-carboxylation of α-CF3 alkenes with CO2 is reported. This approach constitutes a rare example of using electrochemical methods to achieve regioselectivity complementary to conventional metal catalysis. Accordingly, using...
“…(Scheme 1c). [11] Based on our experience in electrochemical synthesis, [12] we envisioned a different scenario for the preparation of gem-difluoroalkenes in which [13] the nucleophilic alkyl radical III generated by electroreduction could selectively react with 1,1trifluoromethylalkenes 1 and the resulting -trifluoromethyl alkyl radical could undergo electrochemical single electron defluorinative reduction.…”
Section: Electroreductive Cross-coupling Of Trifluoromethyl Alkenes and Redox Active Esters For The Synthesis Of Gem-difluoroalkenesmentioning
confidence: 99%
“…To realize the projected electroreductive-defluorinative carbofunctionalization transformation, some criteria have to be fulfilled. The alkyl radical precursor 2 should be more easily reduced than (i) trifluoromethyl alkenes 1 [11] and (ii) gemdifluoroalkenes 3. [14] Moreover, (iii) the nucleophilic radical III generated near the cathode should react with 1 prior to its homocoupling.…”
Section: Electroreductive Cross-coupling Of Trifluoromethyl Alkenes and Redox Active Esters For The Synthesis Of Gem-difluoroalkenesmentioning
An electroreductive access to gem-difluoroalkenes has been developed through the decarboxylative/defluorinative coupling of N-hydroxyphtalimides esters and αtrifluoromethyl alkenes. The electrolysis is performed under very simple reaction conditions in an undivided cell using cheap carbon graphite electrodes. This metal-free transformation features broad scope with good to excellent yields. Tertiary, secondary as well as primary alkyl radicals could be easily introduced. α-aminoacids L-aspartic and Lglutamic acid-derived redox active esters were good reactive partners furnishing potentially relevant gemdifluoroalkenes. In addition, it has been demonstrated that our electrosynthetic approach toward the synthesis of gemdifluoroalkenes could use an easily prepared Kratitsky salt as alkyl radical precursor via a deaminative/defluorinative carbofunctionalization of trifluoromethylstyrene.
“…(Scheme 1c). [11] Based on our experience in electrochemical synthesis, [12] we envisioned a different scenario for the preparation of gem-difluoroalkenes in which [13] the nucleophilic alkyl radical III generated by electroreduction could selectively react with 1,1trifluoromethylalkenes 1 and the resulting -trifluoromethyl alkyl radical could undergo electrochemical single electron defluorinative reduction.…”
Section: Electroreductive Cross-coupling Of Trifluoromethyl Alkenes and Redox Active Esters For The Synthesis Of Gem-difluoroalkenesmentioning
confidence: 99%
“…To realize the projected electroreductive-defluorinative carbofunctionalization transformation, some criteria have to be fulfilled. The alkyl radical precursor 2 should be more easily reduced than (i) trifluoromethyl alkenes 1 [11] and (ii) gemdifluoroalkenes 3. [14] Moreover, (iii) the nucleophilic radical III generated near the cathode should react with 1 prior to its homocoupling.…”
Section: Electroreductive Cross-coupling Of Trifluoromethyl Alkenes and Redox Active Esters For The Synthesis Of Gem-difluoroalkenesmentioning
An electroreductive access to gem-difluoroalkenes has been developed through the decarboxylative/defluorinative coupling of N-hydroxyphtalimides esters and αtrifluoromethyl alkenes. The electrolysis is performed under very simple reaction conditions in an undivided cell using cheap carbon graphite electrodes. This metal-free transformation features broad scope with good to excellent yields. Tertiary, secondary as well as primary alkyl radicals could be easily introduced. α-aminoacids L-aspartic and Lglutamic acid-derived redox active esters were good reactive partners furnishing potentially relevant gemdifluoroalkenes. In addition, it has been demonstrated that our electrosynthetic approach toward the synthesis of gemdifluoroalkenes could use an easily prepared Kratitsky salt as alkyl radical precursor via a deaminative/defluorinative carbofunctionalization of trifluoromethylstyrene.
“…Although electrocatalytic carboxylation of organo (pseudo) halides shows advantage to those with highly reactive metallic powders by using user-friendly and stable anodes, it would be more appealing and practical to achieve such carboxylation without using sacrificial electrodes 52 – 56 . Therefore, we further challenged us with development of an active electrocatalytic system with paired cells.…”
Section: Resultsmentioning
confidence: 99%
“…However, selective electrocatalytic carboxylation of unactivated aryl chlorides and unactivated alkyl halides with CO 2 have rarely been realized 46 – 50 , which are more challenging due to the low reactivity of both unactivated organohalides and CO 2 as well as many competing side reactions, such as protonation, β -H elimination, migration, and homodimerization of the generated organometallic reagents and electrochemical decarboxylation of the products 51 . Besides the limitations in substrate scope, the reductive electrochemical carboxylations mainly rely on the use of sacrificial electrodes 52 – 56 . Fig.…”
Electrochemical catalytic reductive cross couplings are powerful and sustainable methods to construct C−C bonds by using electron as the clean reductant. However, activated substrates are used in most cases. Herein, we report a general and practical electro-reductive Ni-catalytic system, realizing the electrocatalytic carboxylation of unactivated aryl chlorides and alkyl bromides with CO2. A variety of unactivated aryl bromides, iodides and sulfonates can also undergo such a reaction smoothly. Notably, we also realize the catalytic electrochemical carboxylation of aryl (pseudo)halides with CO2 avoiding the use of sacrificial electrodes. Moreover, this sustainable and economic strategy with electron as the clean reductant features mild conditions, inexpensive catalyst, safe and cheap electrodes, good functional group tolerance and broad substrate scope. Mechanistic investigations indicate that the reaction might proceed via oxidative addition of aryl halides to Ni(0) complex, the reduction of aryl-Ni(II) adduct to the Ni(I) species and following carboxylation with CO2.
“…7 In particular, by making use of organolithium/magnesium reagents, regioselective C-C bond formation could be readily achieved, although the functional group compatibility proved somewhat troublesome in this protocol. 8 To ameliorate this status, state-ofthe-art technics leveraging transition-metal catalysis, 9 photoredox catalysis 10 and electrochemistry are actualized, 11 which substantially improve the practicability and compatibility for gem-difluoroalkene construction. To be noted, in addition to typical nucleophilic reagents, radical species generated in situ are Scheme 1 SN2' defluorinative functionalization of trifluoromethyl alkenes also widely explored, allowing for direct alkylation, 10a,b borylation, 10c,d and acylation.…”
An SN2’ defluorinative allylation of trifluoromethylalkenes with readily available allylsilanes to access homoallyl gem-difluoroalkenes was reported. The reaction is triggered by catalytic amount of TBAF with the extruded fluoride in reaction serving as the sustainable activator for organosilanes. The high efficiency, good functional group tolerance, and mild reaction conditions enable the potential utility of this method in synthetic chemistry.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
