Facile synthesis of 2-methyl-4-aryl-1H-pyrrole-3-carbonitriles by cathodic reduction of acetonitrile

Hamrouni, Kaouthar; Batanero, Belén; Barba, Fructuoso; Saied, Taieb; Benkhoud, Mohamed Lamine

doi:10.1016/j.tetlet.2016.09.009

Cited by 4 publications

(2 citation statements)

References 21 publications

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“…A new range of polysubstituted NH‐free pyrroles 83 was produced in high yields (Scheme 26). [26] Kolos and colleagues [27] developed a very efficient two‐component condensation between arylglyoxal 84 and 3‐aminocrotonate 85 . The respective ethyl 5‐aryl‐4‐hydroxy‐2‐methyl‐(1 H )‐pyrrole‐3‐carboxylates 86 were received in moderate yields (Scheme 27).…”

Section: Intra(inter)molecular and Related Reactionsmentioning

confidence: 99%

Recent Advances for the Synthesis of N‐Unsubstituted Pyrroles

et al. 2021

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Pyrroles are an interesting class of heterocyclic compounds due to their widespread use both in medical chemistry and in the chemistry of new materials. Search and development of new effective methods for the synthesis of the pyrrole ring is an urgent task. Along with this, the systematization of already known synthesis methods is an equally important task. Herein, we focused on the results of the synthesis of NH‐pyrroles that have been obtained since 2015.

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Section: Intra(inter)molecular and Related Reactionsmentioning

confidence: 99%

Recent Advances for the Synthesis of N‐Unsubstituted Pyrroles

et al. 2021

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“…In fact, the authors reported that under the described experimental conditions the dimerization reaction to the 3-aminocrotononitrile (Scheme 4) is suppressed, while this dimer is rapidly formed when a platinum anode is used in an undivided cell. They also reported 35 that the 3-aminocrotononitrile anion was generated in high yields when a solution of ACN−Bu 4 NBF 4 was electrolyzed in an undivided cell equipped with a Mg sacrificial anode and a stainless steel cathode, as the 3-aminocrotononitrile anion was stabilized by the presence of Mg 2+ cation. During our research, we have often generated the cyanomethyl anion by cathodic reduction of an acetonitrile−0.1 M Et 4 NBF 4 solution on a platinum cathode in a divided cell, but the amount of the 3aminocrotononitrile obtained at the end of electrolysis was always very small (usually less than 5%).…”

Section: ■ the Electrogenerated Cyanomethyl Anion As A Base: Cs 2 Inc...mentioning

confidence: 99%

The Electrogenerated Cyanomethyl Anion: An Old Base Still Smart

2019

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The cathodic reduction of acetonitrile solutions containing a tetraalkylammonium salt leads to the formation of the cyanomethyl anion ( − CH 2 CN, cyanomethanide). This electrolysis can be carried out under very simple experimental conditions (constant-current electrolyses), using various cathodic materials, controlling the amount of base by simply controlling the amount of charge. Despite the fact that the mechanism for this electrochemical reaction is still debated (and it depends on the cathodic material), the outcome of the electrolysis is the formation of a strong base, − CH 2 CN (pK a 31.3 for acetonitrile in DMSO). The chemical behavior of this electrogenerated base (EGB) strongly depends on its counterion, which in this case is a tetraalkylammonium cation, with a low charge density and thus not coordinated. The very weak interaction between R 4 N + and − CH 2 CN renders the cyanomethyl anion a "naked" ion, and thus highly reactive. In particular, the cyanomethyl anion can react as a base and as a nucleophile. In the first case, it behaves as a strong base and, after deprotonation of a weak acidic substrate, transforms itself into a solvent molecule, acetonitrile, thus generating no byproducts. In the second case, the reactivity as a nucleophile of the cyanomethyl anion obviously depends on the reaction partner. When an electrophile is present in the reaction mixture, a cyanomethylation is obtained (e.g., with aromatic aldehydes, possessing no acidic hydrogen atoms, which undergo nucleophilic attack on the carbonyl carbon atom by − CH 2 CN); on the contrary, when no reagent is present other than acetonitrile and tetraalkylammonium salt, an attack on the parent molecule leads to the acetonitrile dimer, 3-aminocrotononitrile, which in turn can behave as a base and/or as a nucleophile. In this regard, some authors report that it is preferable to carry out the electrogeneration of the cyanomethyl anion under different experimental conditions, i.e., using an undivided cell and a sacrificial magnesium anode. In this way, a Grignard-type reagent is formed (Mg(CH 2 CN) 2 ) which highly stabilizes the cyanomethyl anion, preventing its dimerization. It should be noted that in our laboratory the electrogenerated tetraalkylammonium cyanomethanide was extensively used in various reactions (both acid−base and nucleophile−electrophile, vide infra), and in almost no case, the amount of acetonitrile dimer formed exceeded 5%, confirming the validity of this electrochemical methodology to generate a very efficient base. Moreover, when in the reaction mixture both a weak acid and an electrophile are present, the prevalent reactivity of the cyanomethyl anion is as a base, leaving the possibility of a cyanomethylation reaction to those cases in which no acidic substrate is present. We have successfully used the electrogenerated cyanomethyl anion in many base-induced reactions, as the synthesis of the β-lactam ring (chiral or not), the insertion of carbon dioxide into amines and amino alcohols, the activation of elemental sulfur...

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Synthesis of N,N‐Disubstituted Hydrazines by Electrocatalytic Addition of Hydrazines to α,β‐Unsaturated Carbonyl Compounds

Xu,

Zhang,

et al. 2024

Adv Synth Catal

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A strategy for the synthesis of N,N‐disubstituted hydrazines via the electrocatalytic addition of hydrazine to α,β‐unsaturated carbonyl compounds is reported. The reaction was carried out under constant current electrolytic conditions in an undivided cell. Using this methodology, various N,N‐disubstituted hydrazines are prepared with 57‐94% yields in 40 min. By adding cyclohexanone and acetic acid to the reaction mixture of N,N‐disubstituted hydrazines and heating for 2 h, a "one‐pot" synthesis of N‐substituted indoles has also been developed. Furthermore, based on cyclic voltammetry and controlled experiments, a plausible mechanism involving the radical pathway is proposed.

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Facile synthesis of 2-methyl-4-aryl-1H-pyrrole-3-carbonitriles by cathodic reduction of acetonitrile

Cited by 4 publications

References 21 publications

Recent Advances for the Synthesis of N‐Unsubstituted Pyrroles

Recent Advances for the Synthesis of N‐Unsubstituted Pyrroles

The Electrogenerated Cyanomethyl Anion: An Old Base Still Smart

Synthesis of N,N‐Disubstituted Hydrazines by Electrocatalytic Addition of Hydrazines to α,β‐Unsaturated Carbonyl Compounds

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