External oxidant-free cross-coupling: electrochemically induced aromatic C–H phosphonation of azoles with dialkyl-H-phosphonates under silver catalysis

Author(s): E. O. Yurko ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , T. V. Gryaznova ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , K. V. Kholin ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , V. V. Khrizanforova ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Y. H. Budnikova ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵

Publication date (Electronic): 2018

Journal: Dalton Transactions

Publisher: Royal Society of Chemistry (RSC)

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Abstract

A convenient external oxidant-free method of azole derivatives phosphorylation by dialkyl- H-phosphonates through electrochemical catalytic oxidation in the presence of silver salts (1%) is proposed.

Abstract

A convenient external oxidant-free method of phosphorylation of azole derivatives (benzo-1,3-azoles, 3-methylindole, 4-methyl-2-acetylthiazole) by using dialkyl- H-phosphonates through the catalytic oxidation of their mixture under electrochemical mild conditions (room temperature, normal pressure) in the presence of silver salts or oxide (1%) is proposed. This method allows us to obtain the desired azole dialkylphosphonates with good yield (up to 75%). The transformations of silver and phosphorus precursors and intermediates using cyclic voltammetry, ESR, and NMR spectroscopy were investigated, and a radical process mechanism was proposed. It has been found that AgP(O)(OEt) ₂ is oxidized earlier than other components of the reaction mixture with the elimination of a radical. The ESR spectrum of this radical's adduct was obtained in the presence of the radical trap PBN. Ag ²⁺ is out of the catalytic cycle.

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Chemical Redox Agents for Organometallic Chemistry.

Neil Connelly, William Geiger (1996)

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Redox catalysis in organic electrosynthesis: basic principles and recent developments.

Robert Francke, R. Daniel Little (2014)

Electroorganic synthesis has become an established, useful, and environmentally benign alternative to classic organic synthesis for the oxidation or the reduction of organic compounds. In this context, the use of redox mediators to achieve indirect processes is attaining increased significance, since it offers many advantages compared to a direct electrolysis. Kinetic inhibitions that are associated with the electron transfer at the electrode/electrolyte interface, for example, can be eliminated and higher or totally different selectivity can be achieved. In many cases, a mediated electron transfer can occur against a potential gradient, meaning that lower potentials are needed, reducing the probability of undesired side-reactions. In addition, the use of electron transfer mediators can help to avoid electrode passivation resulting from polymer film formation on the electrode surface. Although the principle of indirect electrolysis was established many years ago, new, exciting and useful developments continue to be made. In recent years, several new types of redox mediators have been designed and examined, a process that can be accomplished more efficiently and purposefully using modern computational tools. New protocols including, the development of double mediatory systems in biphasic media, enantioselective mediation and heterogeneous electrocatalysis using immobilized mediators have been established. Furthermore, the understanding of mediated electron transfer reaction mechanisms has advanced. This review describes progress in the field of electroorganic synthesis and summarizes recent advances.