Electrocatalytic Oxidative Cleavage of Electron-Deficient Substituted Stilbenes in Acetonitrile−Water Employing a New High Oxidation Potential Electrocatalyst. An Electrochemical Equivalent of Ozonolysis

Abstract

A series of symmetrical and unsymmetrical stilbenes bearing two or more strong electron-withdrawing groups were oxidatively cleaved to the corresponding aldehydes in high yield by electrocatalytic anodic oxidation in aqueous acetonitrile employing a new high oxidation potential triphenylamine electrocatalyst. The oxidations apparently involve the corresponding 1,2-diols, which are also converted to aldehydes in high yield under the same conditions.

Contributions of organic electrosynthesis to green chemistry

“…The oxidation potentials of the substituted stilbenes were up to 0.63 V more positive than this of the unsubstituted one. This reaction extends the scope of anodic double bond cleavage to olefins with higher oxidation potential [79].…”

Dehydrogenative reagent-free annulation of alkenes with diols for the synthesis of saturated O-heterocycles

“…The electrolysis was conducted in an undivided cell equipped with a reticulated vitreous carbon (RVC) anode and a platinum plate cathode. The highest yield of the 1,4-dioxane product 4 was 91%, achieved when the reaction system consisted of triarylamine (2,4-Br 2 C 6 H 3 ) 3 N ( 3 ) 46,59 ( E p/2  = 1.48 V vs SCE) as the redox catalyst, i PrCO 2 H as acidic additive and an excess of 2 in refluxing MeCN (entry 1). Other redox mediators that had a lower oxidation potential than 3 , such as (4-BrC 6 H 4 ) 3 N ( 3a , E p/2  = 1.06 V vs SCE), (4-MeO 2 CC 6 H 4 ) 3 N ( 3b , E p/2  = 1.26 V vs SCE) and the imidazole derivative 3c 53 ( E p/2  = 1.19 V vs SCE), were less catalytically effective (entries 2–4).…”

“…1b) 41,42 , probably owing to the relatively high concentration of the alkene radical cation intermediates that were formed on the electrode surface. Moreover, the dimethoxylated product can undergo oxidative decomposition via C–C bond cleavage 43–46 .…”

Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance

“…496 The use of an electron-deficient triarylamine mediator is critical for this electrochemical equivalent of ozonolysis—the mediator has an unusually high oxidation potential of +1.32 V (vs Ag/AgCl). The reaction involves the formation of the corresponding 1,2-diols.…”