Electrochemical synthesis of 1,2,3,4,4,5,6-substituted 1,4-dihydropyridines

Goba, I.; Turovska, Baiba; Stradins, J.; Turovskis, I.; Лиепиньш, Э. Э.; Belyakov, Sergey

doi:10.1007/s10593-007-0029-6

Cited by 11 publications

(4 citation statements)

References 12 publications

(11 reference statements)

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“…Based on these data as well as previous reports on oxidation of DHP derivatives, [6][7][8][9][10][11]24,25 we propose the following mechanism for the electrochemical oxidation of DM compounds (Scheme 2). According to this Scheme, in the first step, DM is oxidized to the DM radical (DM • ) by the loss of one electron and one proton.…”

Section: D-h•••supporting

confidence: 78%

Electrochemical Studies of Newly Synthesized 1,4-Dihydropyridine-Based Hexahydroquinoline Derivatives

Tavakkoli¹,

Goljani²,

Gündüz³

et al. 2020

J. Electrochem. Soc.

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In the present study, six newly synthesized 1,4-dihydropyiridine (DHP) derivatives (isopropyl 2,7,7-trimethyl-5-oxo-4-phenyl-1,4,5,6,7,8-hexahydroquinoline-3-carboxylates) (DM1-DM6) have been studied in water/ethanol mixture (50/50 v/v) by cyclic voltammetry, choronoamperometry and differential pulse voltammetry techniques at a glassy carbon electrode. A detailed oxidation mechanism is proposed. It involves an irreversible diffusion controlled one electron process followed by a disproportionation reaction resulting in the formation of a pyridine. Kinetic and thermodynamic parameters such as charge transfer coefficient (µ), number of electrons (n), exchange current density (J 0 ) and diffusion coefficient (D) were evaluated. The oxidation process is pH-dependent and the pK a of two protonated DHPs and two protonated pyridines were determined. The effect of the phenyl ring substituents on the diffusion coefficient and oxidation potential of the compounds was also studied. Furthermore, the correlation of the oxidation potentials (E ox ) of the DHPs to the highest orbital energy (E HOMO ) was investigated.

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Section: D-h•••supporting

confidence: 78%

Electrochemical Studies of Newly Synthesized 1,4-Dihydropyridine-Based Hexahydroquinoline Derivatives

Tavakkoli¹,

Goljani²,

Gündüz³

et al. 2020

J. Electrochem. Soc.

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“…With an appropriate combination of substrates such as i PrBr ( 1 ) and styrene ( 2 ), the highly selective carbofunctionalization reaction is plausible over various side reactions described above (Scheme B, gray dashed arrows). For example, the reduction of 1 takes place at around −2.0 V (vs SCE) to generate i Pr • ( Int-3 ) upon C–Br cleavage. The subsequent radical addition to 2 is polarity-matched and will occur rapidly to give a new C-centered radical ( Int-6 ).…”

Section: Resultsmentioning

confidence: 99%

Electroreductive Carbofunctionalization of Alkenes with Alkyl Bromides via a Radical-Polar Crossover Mechanism

2020

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Electrochemistry grants direct access to reactive intermediates (radicals and ions) in a controlled fashion toward selective organic transformations. This feature has been demonstrated in a variety of alkene functionalization reactions, most of which proceed via an anodic oxidation pathway. In this report, we further expand the scope of electrochemistry to the reductive functionalization of alkenes. In particular, the strategic choice of reagents and reaction conditions enabled a radical-polar crossover pathway wherein two distinct electrophiles can be added across an alkene in a highly chemo- and regioselective fashion. Specifically, we used this strategy in the intermolecular carboformylation, anti-Markovnikov hydroalkylation, and carbocarboxylation of alkenesreactions with rare precedents in the literatureby means of the electroreductive generation of alkyl radical and carbanion intermediates. These reactions employ readily available starting materials (alkyl halides, alkenes, etc.) and simple, transition-metal-free conditions and display broad substrate scope and good tolerance of functional groups. A uniform protocol can be used to achieve all three transformations by simply altering the reaction medium. This development provides a new avenue for constructing Csp3–Csp3 bonds.

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“…This is extremely improbable since the acidity of the N-H proton is significantly greater than the acidity of methyl group protons. In addition no formation of an exocyclic bond was observed [25] in the protonated dihydroderivative 7. 3,4,5-Trimethoxycarbonyl-1,2,6-trimethyl-3,4-dihydropyridinium perchlorate is a stable compound which is deprotonated in the presence of water regenerating the initial dihydropyridine.…”

mentioning

confidence: 92%

Electrochemical oxidation of 4-monoalkyl-substituted 1,4-dihydropyridines

Turovska

Goba

Turovskis

et al. 2008

Chem Heterocycl Comp

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The electrochemical oxidation of 4-monoalkyl-substituted 1,4-dihydropyridines has been studied in an aprotic medium and in the presence of pyridine. In an aprotic medium the products of oxidation are both 4-alkyl-substituted and 4-unsubstituted pyridines or mixtures of them. On oxidation in acetonitrile of 4- 2,3, were obtained in addition to the oxidized forms. In the presence of base the products of preparative electrolysis of the studied compounds were 4-alkyl-substituted pyridines. The exception was the 4-i-Prsubstituted dihydropyridine which was dealkylated on oxidation even in the presence of base.Dihydropyridines are one of the most investigated classes of organic compounds. The synthesis and reactions of 1,4-dihydropyridines have been examined in detail in reviews [1][2][3][4]. Many compounds of this series possess pharmacological activity. A series of pharmaceuticals [5] has been developed based mainly on 4-arylsubstituted 1,4-dihydropyridines. Antioxidant properties have also been confirmed for the heterocycle itself in reactions with various radicals [6,7]. On the other hand study of the redox reaction of the dihydropyridine ring is also important for the reason that its oxidation is the main metabolism of dihydropyridines.The attention of electrochemists is mainly attracted [8][9][10][11][12][13] by the oxidation of 4-methyl-, 4-aryl-1,4-dihydropyridines or those unsubstituted in position 4. In all the mentioned cases proton is split off from the position 4 of the ring on oxidation. N Me H Me R H COOMe MeOOC 1-5 1 R = Me, 2 R = Et, 3 R = n-Pr, 4 R = i-Pr, 5 R = i-Bu

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Electrochemical synthesis of 1,2,3,4,4,5,6-substituted 1,4-dihydropyridines

Cited by 11 publications

References 12 publications

Electrochemical Studies of Newly Synthesized 1,4-Dihydropyridine-Based Hexahydroquinoline Derivatives

Electrochemical Studies of Newly Synthesized 1,4-Dihydropyridine-Based Hexahydroquinoline Derivatives

Electroreductive Carbofunctionalization of Alkenes with Alkyl Bromides via a Radical-Polar Crossover Mechanism

Electrochemical oxidation of 4-monoalkyl-substituted 1,4-dihydropyridines

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