Reductive cyclization of o-(3-butenyl)fluorobenzene at mercury and lead cathodes

Loffredo, David M.; Swartz, James E.; Kariv-Miller, Essie

doi:10.1021/jo00286a030

Cited by 8 publications

(9 citation statements)

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“…The cyclization pathway was proposed to proceed via the same aryl 25 Middle: Defluorinative reductive cyclization. 27 Bottom: Mechanistic proposal for reductive hydrodefluorination. [25][26][27] Hydrodefluorination of a limited number of 7-piperazinoquinolones under electroreductive conditions was reported by Albini and co-workers (Figure 3).…”

Section: Cleavage Of C(sp 2 )-F Bondsmentioning

confidence: 99%

“…27 Bottom: Mechanistic proposal for reductive hydrodefluorination. [25][26][27] Hydrodefluorination of a limited number of 7-piperazinoquinolones under electroreductive conditions was reported by Albini and co-workers (Figure 3). 28 Similar to Kariv-Miller's findings, 25 selective monodefluorination of position 8 in 6,8-difluorinated lomefloxacin was achieved after 2 F/mol and defluorination of the monofluoride-containing enoxacin was observed.…”

Section: Cleavage Of C(sp 2 )-F Bondsmentioning

confidence: 99%

“…25 Middle: Defluorinative reductive cyclization. 27 Bottom: Mechanistic proposal for reductive hydrodefluorination. [25][26][27] Fig.…”

Section: Reviewmentioning

confidence: 99%

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Electrosynthetic C–F bond cleavage

2022

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Section: Cleavage Of C(sp 2 )-F Bondsmentioning

confidence: 99%

Section: Cleavage Of C(sp 2 )-F Bondsmentioning

confidence: 99%

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Electrosynthetic C–F bond cleavage

2022

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“…Kariv-Miller's group investigated the cathodic behavior of 1-(3-butenyl)-2-fluorobenzene at mercury and lead cathodes in DMF with Bu 4 NBF 4 as the supporting electrolyte. Under heterogeneous conditions, the cyclized product dominated for both cathodes: about 72% at 0 °C . This percentage could, however, be misleading.…”

Section: Resultsmentioning

confidence: 94%

“…Under heterogeneous conditions, the cyclized product dominated for both cathodes: about 72% at 0 °C. 104 This percentage could, however, be misleading. Indeed, when H 2 O was added to a solution where redox catalysis is probably involved (presence of dimethylpyrrolidinium-Hg), the percentage decreased to 43%, suggesting that part of 72% is due to a carbanionic cyclization.…”

Section: +mentioning

confidence: 99%

Radical Clocks, Solvated Electrons, and Magnesium. Heterogeneous versus Homogeneous Electron Transfer. Selectivity at Interfaces

Hazimeh¹,

Kanoufi²,

Combellas³

et al. 2008

J. Phys. Chem. C

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Ammonia solutions of solvated electrons may be prepared by electrolyzing the solvent in the presence of Mg(BF4)2 and Mg++ provided by a magnesium anode. The reactions of these solutions (−40 °C) with the two radical clocks 1-bromo-2-(3-butenyl)benzene 1 and 1-(allyloxy)-2-bromobenzene 7 (0.007−0.008 M) are examined. Both probes yield very high percentages of cyclized products (>97%) when the concentration of solvated electrons is low (0.028 M). These percentages diminish when the metallic character of the solution is increased (0.183 M concentration in solvated electrons). These results strongly contrast with those obtained for the reactions of these radical probes with magnesium turnings or potassium lumps in THF. Under these conditions, the percentages of cyclized products are lower than 4%. We propose that the main cause of this contrasting behavior is the higher reducing efficiency of the heterogeneous electron transfer with respect to the homogeneous electron transfer. This holds even if the reducing agent in the bulk is one of the strongest known reducing agents (solvated electron). The causes for the striking difference between heterogeneous and homogeneous electron transfer are discussed in terms of selectivity within a double-layer perspective. These differences allow the rationalization of an apparent discordance. The behavior of MgX2 (X = halogen) under pulse radiolysis conditions (Mostafavi's group) shows that MgX2 are so weakly oxidizing that in most solvents they do not react with the solvated electron. Nevertheless, the reduction of MgX2 by alkali metals (Rieke's method) is the basis for the preparation of very active slurries of magnesium. This principle has been widely extended for the preparation of various metallic nanoparticles. The difference between homogeneous and heterogeneous electron transfer to MgX2 lies at the heart of the problem as explained in the framework of molecular electrochemistry at the cathode surface. Kinetic treatment of the selectivity at the metal−liquid interface is contrasted with selectivity obtained in homogeneous solution.

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