Mediatory System Research Articles

Halogen Mediated Electrochemical Synthesis: Facial Accesses to Dibenzothiophenes and Spirooxindoles

Electrochemical oxidative transformations using a halide as an oxidative mediator are useful for facial accesses to a variety of important organic compounds in the material and biological research fields. We have revealed the unique mediatory ability of anodically generated bromonium ion equivalent in the electrochemical synthesis of the thienoacenes [1].In this presentation we will report two types of transformation using the mediatory system, which enable the formation of a series of crucial compounds. The first one is electrochemical synthesis of dibenzothiophene derivatives, one of the most important frameworks in the field of material science and pharmaceuticals. Several bis(biaryl) disulfides are efficiently converted to dibenzothiophenes by the electrochemical oxidation [2]. The second is the semi-pinacol rearrangement of tetrahydro-β-carbolines affording 3-spirooxindoles, which have unique three-dimensional structures and potent bioactivity [3]. In these reactions, the anodically generated bromonium ion equivalent as a halogen mediator was essential and efficiently promoted the transformation.[1] Mitsudo, K.; Matsuo, R.; Yonezawa, T.; Inoue, H.; Mandai, H.; Suga, S: Angew. Chem. Int. Ed. 2020, 59, 7803−7807.[2] Mitsudo, K.; Tachibana, Y.; Sato, E.; Suga, S: Org. Lett. 2022, 24, 8547−8552.[3] Sato, E.; Kangawa, S.; Mitsudo, K.; Suga, S. Chem. Lett. 2022, 51, 1067–1069.

ChemInform Abstract: The First Electrocatalytic Stereoselective Multicomponent Synthesis of Cyclopropanecarboxylic Acid Derivatives.

AbstractThe title synthesis from aldehydes, alkyl cyanoacetate and dialkyl malonate proceeds in a simple beaker and allows multigram‐scale synthesis.

ChemInform Abstract: Viologen as Catalytic Organic Reductant: Electro‐Reductive Dimerization of Aryl Bromides in a Pd/Viologen Double Mediatory System.

AbstractThe Pd‐catalyzed electro‐reductive coupling of aryl bromides is achieved using a small amount of viologen additive as an in situ recyclable organic reductant.

Viologen as catalytic organic reductant: electro-reductive dimerization of aryl bromides in a Pd/viologen double mediatory system

Abstract Viologen can be used as an in situ recyclable organic reductant. Pd-catalyzed electrochemical reductive coupling of aryl bromides was performed by using a catalytic amount of viologen to afford the corresponding biaryls in good to moderate yields.

Electrocatalytic cascade multicomponent assembling: stereoselective one-pot synthesis of the substituted 3-azabicyclo[3.1.0]hexane-1-carboxylate system from aldehyde, malononitrile, malonate and methanol

Electrolysis of aromatic aldehydes, malononitrile and malonate in methanol in an undivided cell in the presence of sodium bromide–sodium methoxide as double mediatory system results in the stereoselective formation of methyl (1 R ∗,5 R ∗,6 R ∗) 6-substituted 5-cyano-4,4-dialkoxy-2-oxo-3-azabicyclo[3.1.0]hexane-1-carboxylates in 50–70% yields.

Electrocatalytic multicomponent cyclization of an aldehyde, malononitrile and a malonate into 3-substituted-2,2-dicyanocyclopropane-1,1-dicarboxylate—the first one-pot synthesis of a cyclopropane ring from three different molecules

Electrolysis of an aldehyde, malononitrile and a malonate in an alcohol in an undivided cell in the presence of sodium acetate–sodium halide as a double mediatory system results in the formation of 3-substituted-2,2-dicyanocyclopropane-1,1-dicarboxylates in 40–60% yields.

Stereoselective electrocatalytic transformations of malononitrile and aromatic aldehydes into (1R,5S,6R)*-4,4-dialkoxy-2-amino-6-aryl-1,5-dicyano-3-azabicyclo[3.1.0]hex-2-enes

Electrolysis of aromatic aldehydes and malononitrile in alcohols in an undivided cell in the presence of a NaBr-NaOAc mediatory system stereoselectively gave bicyclic compounds containing the cyclopropane and pyrroline fragments in 60 to 70% yields. In the bicyclic products, the benzene and pyrroline rings are on different sides of the cyclopropane ring.

Electroreduction of aliphatic esters by using alkali metal ion–crown ether complexes as mediators

The electroreduction of methyl decanoate ( 1) by using alkali metal ion-free Bu 4NClO 4 as a supporting electrolyte and platinum as anode and cathode was carried out in the presence of several kinds of alkali metal ion sources. The use of Bu 4NClO 4 as a supporting electrolyte without alkali metal ions gave only a trace amount of the reduced product. The addition of 0.05 equiv. of LiClO 4 or NaClO 4 into this electroreduction system gave the reduction product, 2-alkoxytetrahydrofurans 5 in ca. 20% yield. In this electrolysis, the ligand effect of the alkali metal ion sources was remarkably noted, that is, the electroreduction using sodium ion–crown ether complexes, especially, sodium ion—the polymeric crown ether ligands such as poly(vinylbenzo-15-crown-5- co-styrene) complex, greatly increased the efficiency of the electroreduction. It is plausible that alkali metal (0) species are electrogenerated from alkali metal ions and react as active reductants to reduce the aliphatic esters and the mediatory system is established in this electrolysis system.

Double Mediatory System Involving a Flavin Analog and a p-Benzoquinone Derivative for Photoinduced Electrochemical Oxidation of Benzyl Alcohol to Benzaldehyde in Acetonitrile

Abstract The photoinduced electrochemical oxidation of benzyl alcohol to benzaldehyde in acidic acetonitrile proceeded with practically 100% product selectivity and ca. 100% current efficiency under visible-light irradiation in the presence of riboflavin-2′,3′,4′,5′-tetraacetate (RF) as a mediator. A double mediatory system involving duroquinone as well as RF resulted in remarkable acceleration of the benzaldehyde formation with maintenance of both the high product selectivity and high current efficiency.

ChemInform Abstract: A Novel Ru(VII)/Ru(IV) Mediatory System for Electrooxidation of Primary and Secondary Alcohols, Leading to Aldehydes and Ketones.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A Novel Ru(VII)/Ru(IV) Mediatory System for Electrooxidation of Primary and Secondary Alcohols, Leading to Aldehydes and Ketones

Abstract A soluble Ru(VII)/Ru(IV) redox system in MeCN/H2O(9/1 v/v)-Bu4NOH-(Pt/Pt) was found to be a mild oxidizing method for the electrochemical conversion of primary and secondary alcohols into their corresponding aldehydes and ketones under basic conditions.

ChemInform Abstract: Electrochemical Wacker Type Reaction with a Double Mediatory System Consisting of Palladium Complex and Tri(4‐bromophenyl)amine.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Electrochemical Wacker Type Reaction with a Double Mediatory System Consisting of Palladium Complex and Tri(4-bromophenyl)amine

Abstract The electrochemical Wacker type oxidation of terminal olefins by using palladium chloride or palladium acetate and tri(4-bromophenyl)amine as a recyclable mediator in either a divided cell or an undivided cell afforded the corressponding methyl ketones in good yields.

ChemInform Abstract: Indirect Electrooxidation of Alcohols by a Double Mediatory System with Two Redox Couples of (R2N+=O)/R2NO× and (Br× or Br+)/ Br‐ in an Organic‐Aqueous Two‐Phase Solution.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Indirect electrooxidation of alcohols by a double mediatory system with two redox couples of [R2N+:O]/R2NO.cntdot. and [Br.cntdot. or Br+]/Br- in an organic-aqueous two-phase solution

An indirect electrooxidation method for alcohol to aldehyde to ketone conversion has been developed. This method, applicable to chemoselective oxidation, employs two redox couples, consisting of 2,2,6,6-tetremathyl-piperidine-1-oxyl derivatives and active bromine species

ChemInform Abstract: Indirect Electrooxidation of Alcohols by a Double Mediatory System (R2N+=O)/R2N‐O· and (Br· or Br+)Br‐ Redoxes.

AbstractElectrolysis of undecanol (II) in the presence of 4‐benzyloxy‐2,2,6,6‐tetramethylpiperidine 1‐oxyl (I) and sodium bromide as recyclable reagents yields the aldehyde (III) and the ester (IV), depending on the amount of the piperidine 1‐oxyl used.

Indirect Electrooxidation of Halohydrins by a Double Mediatory System of Ru(VIII)/Ru(IV) and [Cl+]/Cl−. Optimization for the Oxidation of 1,3-Dichloro-2-propanol to 1,3-Dichloroacetone

Abstract Optimum conditions for the electrooxidation of 1,3-dichloro-2-propanol (1) to 1,3-dichloroacetone (2) by using a double redox system of Ru(VIII)/Ru(IV) and [Cl+]/Cl− are elucidated. The electrolysis of 1 in an AcOEt–aqueous NaCl (2:3 v/v) system buffered at pH 2–4 in a divided cell at 0–5°C gives 2 in 98% selectivity toward 1,1,3-trichloroacetone (3) under the current efficiency of 92%.

Indirect Electrooxidation of Alcohols by a Double Mediatory System with [R2N+= O]/R2N-O . and [Br. or Br+]Br-Redoxes

A double mediatory system consisting of N-oxoammonium salts and active bromine species, generated from 2,2,6,6-tetramethylpiperidine-1-oxyl derivatives and bromide ion as recyclable reagents, is useful for the selective electrooxidation of primary and secondary alcohols to aldehydes and ketones, respectively, in an aqueous-organic two-phase system.

ChemInform Abstract: Indirect Electrooxidation of Alcohols and Aldehydes by Using a Double Mediatory System Consisting of RuO4/RuO2 and Cl+/Cl‐ Redoxes in an Aqueous‐Organic Two‐Phase System.

AbstractDas elektrolytisch regenerierbare doppelte Redoxsystem RuO4/RuO2‐Cl+/Cl′ wird zur Oxidation von Hydroxyverbindungen eingesetzt.

Indirect electrooxidation of alcohols and aldehydes by using a double mediatory system consisting of ruthenium tetraoxide/ruthenium dioxide and chlorine cation/chlorine anion redoxes in an aqueous-organic two-phase system

Indirect electrooxidation of alcohols and aldehydes by using a double mediatory system consisting of ruthenium tetraoxide/ruthenium dioxide and chlorine cation/chlorine anion redoxes in an aqueous-organic two-phase system