Electrochemical reduction amides

The electrochemical reduction of aliphatic amides in dilute hydrochloric acid will tolerate other functional group.s active towards the alternative hydride reducing agents. With aliphatic amides the electrochemical step generally leads to the aldehyde because the intermediate imine is rapidly hydrolysed under the conditions... 

Oxazolidinediones can be obtained from electrochemical reduction of a-halo amides in the presence of carbon dioxide. Originally, the 2,4-oxazolidine-... 

The electroreduction of iV-(haloethyl)amides 8 at a mercury cathode in DMF or acetonitrile gives rise to the corresponding iV-(2,2-dichlorovinyl)amides 9 in good to excellent yields (equation 5)25. The electrochemical reduction of fluorinated fullerene has been reported26. 

Both aliphatic and aromatic esters may be converted to amides by electrochemical reduction of the ester in the presence of an amine in a divided cell as in Eq. (23) [95]. This reaction is not formally a reduction, but the reaction does not occur without passage of current. The mechanism is likely formation of an anion radical with abstracts a proton from ammonia to form amide ion. The amide ion subsequently displaces alkoxide in a chain reaction to form carboxamide. 

The electrochemical reduction of (TPPFe)20 was carried out in dimethyl form-amide by Kadish et al.3s) and whereas for the monomer... 

The electrochemical reduction of CO2 in the presence of dimethylamine and [Ru(bipy)2(CO)2] as the catalyst in anhydrous acetonitrile gives dimethylform-amide and formate. Ruthenium carbamoyl complexes are likely intermediates, and the formation of [(bipy)2Ru(CO)(CONMe2)] was confirmed by FT-IR and H Dimethyl formamides are also formed if CO2 is reduced by H2 in the presence of dimethylamine. The catalysts employed were [RuH(Cl)(CO)L3], [RUCI2L3], [OsH(C1)L3], [Os(H)2C1(CO)L3], [IrCl(CO)L2], [Pt2(dppm)3],... 

Subsequent research showed the SrnI mechanism to occur with many other aromatic compounds. The reaction was found to be initiated by solvated electrons, by electrochemical reduction, and by photoinitiated electron transferNot only I, but also Br, Cl, F, SCeHs, N(CH3)3, and 0P0(0CH2CH3)2 have been foimd to serve as electrofuges. In addition to amide ion, phosphanions, thiolate ions, benzeneselenolate ion (C HsSe"), ketone and ester enolate ions, as well as the conjugate bases of some other carbon acids, have been identified as nucleophiles. The SrnI reaction was observed with naphthalene, phenanthrene, and other polynuclear aromatic systems, and the presence of alkyl, alkoxy, phenyl, carboxylate, and benzoyl groups on the aromatic ring does not interfere with the reaction. ... 

Electrochemical redox studies of electroactive species solubilized in the water core of reverse microemulsions of water, toluene, cosurfactant, and AOT [28,29] have illustrated a percolation phenomenon in faradaic electron transfer. This phenomenon was observed when the cosurfactant used was acrylamide or other primary amide [28,30]. The oxidation or reduction chemistry appeared to switch on when cosurfactant chemical potential was raised above a certain threshold value. This switching phenomenon was later confirmed to coincide with percolation in electrical conductivity [31], as suggested by earlier work from the group of Francoise Candau [32]. The explanations for this amide-cosurfactant-induced percolation center around increases in interfacial flexibility [32] and increased disorder in surfactant chain packing [33]. These increases in flexibility and disorder appear to lead to increased interdroplet attraction, coalescence, and cluster formation. 

Porphyrin complexes are particularly suitable cores to construct dendrimers and to investigate how the behavior of an electroactive species is modified when surrounded by dendritic branches. In particular, dendritic porphyrins can be regarded as models for electron-transfer proteins like cytochrome c [42, 43]. Electrochemical investigation on Zn-porphyrins bearing polyether-amide branches has shown that the first reduction and oxidation processes are affected by the electron-rich microenvironment created by the dendritic branches [42]. Furthermore, for the third generation compound all the observed processes become irreversible. 

The reduction is usually made in a multi-compartment electrochemical cell, where the reference electrode is isolated from the reaction solution. The solvent can be water, alcohol or their mixture. As organic solvent A,A-dimethyl form amide or acetonitrile is used. Mercury is often used as a cathode, but graphite or low hydrogen overpotential electrically conducting catalysts (e.g. Raney nickel, platinum and palladium black on carbon rod, and Devarda copper) are also applicable. 

An electrochemical method for the synthesis of a series of 4-(alkylamino)-2-phenyloxazolines 139a-f from A -(2,2-dichlorovinyl)amides 135 has been reported. The starting A -(2,2-dichlorovinyl)amide 135, readily available from chloral and amides, undergoes facile reaction with amines to give 136. Cathodic reduction of 136 generates chlorocarbanionic intermediates 137 and 138 that... 

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