Recent Advances in the Electrochemical Reduction of Substrates Involving N−O Bonds

Abstract

In this review,t he versatile and rich chemistry for the electrochemical reductiono fs ubstrates involving N À Ob onds is surveyed. By the cathodic treatment of nitro,n itroso and other oxygenated organic nitrogen substrates,v ersatile andr eactive intermediates are formed which can be subsequently converted to high value-added products. In many examples,n itrogen heterocycles are selectively formed, but, also depending on the electrolytic conditions, free oximes,n itrones,a mines and other entities can be obtained as well. Ther ecent decades have witnessed twom ajor advances-(i)g oing directly to more complext arget molecules and (ii)c onductingt he electrolysesi nm uch simpler set-ups.Both improvements make the cathodic access of the target compoundsm uch more practical and scalable. 1I ntroduction 2N itro Derivatives 2.1 IntermolecularReactions 2.2 IntramolecularReactions:Synthesis of Heterocycles 3O ximes 4O ther Functionalities 5C onclusions

Cathodic Corrosion of Metal Electrodes—How to Prevent It in Electroorganic Synthesis

“…The cathodic conversion of N,O bonds is of actual interest and different electrode systems are employed. 254 Wirtanen, Waldvogel et al applied leaded bronze cathodes in the synthesis of 2 H -2-(aryl)benzo[ d ]-1,2,3-triazoles and 2 H -2-(aryl)benzo[ d ]-1,2,3-triazole N -oxides ( Scheme 22 ). 255 The leaded bronzes outperformed the lead as a cathode material, and among leaded bronzes, CuSn7Pb15 was found to be the most suitable cathode.…”

The preparation and applications of amides using electrosynthesis

“…27 Scheme 9 Electrochemical quinazolinone synthesis and scope. 28,29 did not undergo the desired Favorskii rearrangement (though did still produce amide products). 30 The mechanism for this reaction is shown in Scheme 12, starting with iodide oxidation to produce I 2 , which reacts with 18 to form an α-iodoketone 19.…”

“…These conditions were tolerated by a range of functional groups to give reasonably good yields. 27 There are also examples of amide bonds being formed from nitrile groups other than in MeCN, such as the work of Estrada and Rieker from 1994, 28,29 which showed how 2-nitrobenzonitrile 14 could be converted into quinazolinones 15 in the presence of various alcohols. This reaction employed a mercury pool cathode and a carbon anode in an undivided cell and is shown in Scheme 9.…”

“…Most examples tested gave moderate to good yields, however, some exceptions include dibenzyl ketones bearing electron-donating substituents (such as OMe), as these Scheme 10 Proposed mechanism for electrochemical quinazolinone synthesis. 28,29 Scheme 7 Electrochemical iodide oxidation and reaction with MeCN. 26 Scheme 8 Anodic flow oxidation in the presence of MeCN and H 2 O to produce amides.…”

Synthesis, characterization and photostability study of triazole derivatives

“…Heterocyclic compounds, which have at least 2 different atom types in the ring, are the most prevalent form of organic substrate [1][2][3]. Triazole, likewise famed as pyrrodiazole, it is an example of a class of organic heterocyclic compounds that contain nitrogen.…”