Electrochemical Friedel–Crafts-type amidomethylation of arenes by a novel electrochemical oxidation system using a quasi-divided cell and trialkylammonium tetrafluoroborate

• Hisanori Senboku,
• Mizuki Hayama and
• Hidetoshi Matsuno

Beilstein J. Org. Chem. 2022, 18, 1040–1046, doi:10.3762/bjoc.18.105

• solvent and a divided cell with a low temperature (−78 °C) and a relatively high concentration of the supporting electrolyte are necessary, the cation pool method [21] developed by Yoshida and Suga was effective for electrochemical oxidation-induced Friedel–Crafts-type amidomethylation (path d in Scheme 1

• amidoalkylation, the desired products were not obtained/detected by 1H NMR. In contrast, it was reported that anisole [9][11][23] and 1,3,5-trimethylbenzene [23] could react with acyliminium ions generated by the chemical [9][11] or cation pool method [23] to produce amidomethylated products. These results

• indicate that the present electrochemical amidomethylation seems to be relatively less reactive than other chemical methods and the cation pool method. On the other hand, similar electrolysis of 1,3-dimethoxybenzene gave a mixture of products including regioisomeric mono-amidomethylation products together

Stereoselective nucleophilic addition reactions to cyclic N-acyliminium ions using the indirect cation pool method: Elucidation of stereoselectivity by spectroscopic conformational analysis and DFT calculations

• Koichi Mitsudo,
• Junya Yamamoto,
• Tomoya Akagi,
• Atsuhiro Yamashita,
• Masahiro Haisa,
• Kazuki Yoshioka,
• Hiroki Mandai,
• Koji Ueoka,
• Christian Hempel,
• Jun-ichi Yoshida and
• Seiji Suga

Beilstein J. Org. Chem. 2018, 14, 1192–1202, doi:10.3762/bjoc.14.100

• , Okayama 700-8530, Japan Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan 10.3762/bjoc.14.100 Abstract In this study, six-membered N-acyliminium ions were generated by the “indirect cation pool” method and

• consistent with the Steven’s hypothesis. Keywords: cation pool; conformation; electroorganic synthesis; N-acyliminium ion; NMR analysis; piperidine; Introduction Cyclic amines are significant key motifs in pharmaceutical and natural products because a variety of compounds bearing those moieties exhibit

• very efficiently yield carbon–carbon bond-formation products. In addition, this research lead to the development of an indirect cation pool method that enables the creation of the cation pool by reacting a cation precursor having a C–S bond with an electrochemically generated ArS(ArSSAr)+ as the cation

Switching the reaction pathways of electrochemically generated β-haloalkoxysulfonium ions – synthesis of halohydrins and epoxides

• Akihiro Shimizu,
• Ryutaro Hayashi,
• Yosuke Ashikari,
• Toshiki Nokami and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2015, 11, 242–248, doi:10.3762/bjoc.11.27

• the reaction of alkenes with Br2 and I2 [2]. However, the most straightforward method is the reaction of alkenes with halogen cations such as Br+ and I+. The I+ cation pool exists as reported by Filimonov et al. [3], although the used solvent is concentrated sulfuric acid which is therefore not

• compatible with most organic compounds. Electrochemical oxidation [4][5][6][7][8][9][10][11] is a potent technique to generate and accumulate highly reactive cationic species in solution (the “cation pool” method) [12][13][14][15][16][17]. Although halogen cations are too unstable to accumulate in solution

• mechanism involving the back-side attack of the alkoxide ion to form epoxide 6a. Reactions of β-iodoalkoxysulfonium ions generated from (Z)-5-decene We next examined the reactions of β-iodoalkoxysulfonium ion 3a-I generated by the reaction of (Z)-5-decene (2a) with I+/DMSO (1-I) cation pool [22] (Scheme 1

Redox active dendronized polystyrenes equipped with peripheral triarylamines

• Toshiki Nokami,
• Naoki Musya,
• Tatsuya Morofuji,
• Keiji Takeda,
• Masahiro Takumi,
• Akihiro Shimizu and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2014, 10, 3097–3103, doi:10.3762/bjoc.10.326

• polystyrene having peripheral bromo groups was prepared from the dendronization of unfunctionalized polystyrene with dendritic diarylcarbenium ions bearing peripheral bromo groups using the “cation pool” method. The palladium-catalyzed amination of the peripheral bromo groups with diarylamine gave dendronized

• unsuccessful. Low-temperature electrochemical oxidation of dendrimer 5 using the “cation pool” method [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] did not give the corresponding dendritic diarylcarbenium ion even, when subjected to excess capacitance (up to 5.0 F/mol). Next, we examined

• the “graft-from” approach (Figure 3). The low-temperature electrochemical oxidation of dendrimer 4 using the “cation pool” method was performed in CD2Cl2, and the resulting anodic solution was transferred to NMR tubes. Low-temperature NMR analysis indicated that an accumulation of dendritic

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• for the generation of the N-acyliminium ion and trapping with solvent (e.g., methanol), regenerating the N-acyliminium ion through treatment with a Lewis acid (quenching with the nucleophile) can be overridden by the “cation pool” method [17]. The cation pool methodology relies on the low temperature

• oxidise the nucleophile than the amide precursor. This circumvents the need to prepare, trap and release the N-acyliminium cation under more favourable conditions, allowing the direct α-alkylation or arylation of carbamates (Scheme 3); the cation pool method has been extensively studied [17][18][19][20

• radicals from the cation pool method [24][25]. Indirect electrolysis methods The only indirect anodic oxidation method to perform the Shono-oxidation with a thiophenyl electroauxiliary has been reported by Fuchigami and co-workers [36]. Using a catalytic triarylamine redox mediator, anodic

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• electrochemistry of heterocyclic compounds are also available [27][28][29]. However, recent innovations in electrosynthesis such as the cation pool method or the development of novel electron transfer mediators also have a significant impact on heterocyclic chemistry [30][31]. This review focuses upon both anodic

• coupling. In addition to enol ethers 1, vinyl sulfides and ketene acetals have successfully been cyclized according to Scheme 2 [34][35][36]. An interesting modification of this anodic coupling method was achieved by Yoshida, Nokami and co-workers using the “cation pool” concept [37][38][39]. In this

• approach, the anodic oxidation of olefins was combined with a sequential chemical oxidation in a one-pot fashion (Scheme 3) [39]. By using DMSO instead of methanol as nucleophilic co-solvent for electrolysis, a pool of alkoxysulfonium ions 7 is generated from tosylamine 5. The generation of the cation pool

A practical microreactor for electrochemistry in flow

• Kevin Watts,
• William Gattrell and
• Thomas Wirth

Beilstein J. Org. Chem. 2011, 7, 1108–1114, doi:10.3762/bjoc.7.127

• the product at a flow rate of 10–15 µL·min−1 with a current of 0.6 mA. Yoshida reported a method of producing carbocations such as 1 in the absence of a suitable nucleophile (the "cation pool" method). This is an unconventional method because the ions generated are unstable and usually need to be

• be used in different subsequent reactions (Scheme 1). The first reaction studied was a Friedel–Crafts reaction of aromatic compounds. In comparison with the "cation pool" method, the "cation flow" method was far more successful for this reaction, producing the monoalkylated product 2 in 92% yield in

Generation of pyridyl coordinated organosilicon cation pool by oxidative Si-Si bond dissociation

• Toshiki Nokami,
• Ryoji Soma,
• Yoshimasa Yamamoto,
• Toshiyuki Kamei,
• Kenichiro Itami and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2007, 3, No. 7, doi:10.1186/1860-5397-3-7

• organosilicon cation stabilized by intramolecular pyridyl coordination was effectively generated and accumulated by oxidative Si-Si bond dissociation of the corresponding disilane using low temperature electrolysis, and was characterized by NMR and CSI-MS. Findings We have recently developed the "cation pool

• using the "cation pool" method. Organosilicon cations are known to be extremely unstable and difficult to accumulate in solution [7][8][9][10][11]. Organosilicon cations having appropriate donor ligands are, however, reasonably stable to accumulate in solution and many examples of such donor-stabilized

• oxidation of 1d was carried out to generate and accumulate the corresponding organosilicon cation 3d (Scheme 3). Nature of the counter anion was very important. When 1d was oxidized in the presence of Bu4NBF4, which is a common supporting electrolyte for the "cation pool" method, fluoride was introduced on