Silver(I)-catalyzed oxidative decarboxylation of acids by peroxydisulfate. Role of silver(II)

Abstract

Silver (1) is involved in an efficient catalysis of the oxidative decarboxylation of acids by peroxydisulfate ion in aqueous solutions. The rate of decarboxylation is first order in silver(1) and peroxydisulfate, but zero order in carboxylic acid. The formation of alkane, alkene, alcohol, and ketone as products are attributed to alkyl radical intermediates. The synergistic effect of copper(I1) as a cocatalyst occurs at low concentrations, and is associated with the efficient trapping of alkyl radicals. The product distribution and the stoichiometry of the oxidative decarboxylation can be deliberately altered by considering the mechanistic effects of silver(I), copper(II), and carboxylic acid concentrations. A mechanism is proposed in which the silver(I1) species is formed as a metastable intermediate and it plays an important role in the specific and efficient oxidation of the carboxylic acid function.he readily available peroxydisulfate ion, SZO~*-, is

One‐Pot Three‐Step Synthesis of Naphtho[2,3‐a]carbazole‐ 5,13‐diones using a Tandem Radical Alkylation–Cyclization– Aromatization Reaction Sequence

“…[38] This includes silver-catalyzed decarboxylic radical alkylation [39][40][41] yielding bromide 3, palladium-catalyzed cyclization to offer tetracyclic product 4, and DBU-assisted aromatization (Scheme 1). This strategy is very efficient yielding the target compound 5 in a 40% three-step overall yield.…”

Microwave-Assisted One-Step Synthesis of 2,5-Disubstituted-1,3,4-Oxadiazoles Using 1,4- Bis(triphenylphosphonium)-2-Butene Peroxodisulfate

“…The reaction was found to proceed smoothly under microwave irradiation within 25 min whereas under reflux conditions, 12 h were required. 19 The products were isolated by simple cold aqueous work-up followed by either solvent extraction or precipitation and were finally purified by column chromatography wherever necessary, to afford pure 2,5-disubstituted 1,3,4-oxadiazole.…”

Transition Metal‐Mediated Direct CH Arylation of Heteroarenes Involving Aryl Radicals

“…Baran and others suggested that the SO 4 C À intermediate was the oxidizing agent but one cannot rule out the role of the Ag(II) species, as suggested by Kochi for the homolytic decarboxylation of carboxylic acids using a Ag(I)/persulfate system. [95] The arylation was thus carried out in the presence of 6 equivalents of allyl acetate which is known as a radical trap for SO 4 C À , but no impact on reaction yield was observed, indicating that arylboronic acid is more likely oxidized by Ag(II). Authors also suggested that boron "ate" derivatives might be more susceptible to single-electron oxidation than trigonal boron species, and a solvent or a pyridine molecule might interact with the boron atom to facilitate the process.…”