Decarboxylative Halogenation and Cyanation of Electron-Deficient Aryl Carboxylic Acids via Cu Mediator as Well as Electron-Rich Ones through Pd Catalyst under Aerobic Conditions

Abstract

Simple strategies for decarboxylative functionalizations of electron-deficient benzoic acids via using Cu(I) as promoter and electron-rich ones by employing Pd(II) as catalyst under aerobic conditions have been established, which lead to smooth synthesis of aryl halides (-I, Br, and Cl) through the decarboxylative functionalization of benzoic acids with readily available halogen sources CuX (X = I, Br, Cl), and easy preparation of benzonitriles from decarboxylative cyanation of aryl carboxylic acids with nontoxic and low-cost K4Fe(CN)6 under an oxygen atmosphere for the first time.

Synthesis of Aryl Iodides from Arylhydrazines and Iodine

“…[CAS: 609-73-4]. 26 Yellow solid, 108.6 mg, 87% (isolated yield), mp 48–49 °C; 1 H NMR (400 MHz, CDCl 3 ): δ 8.05 (d, J = 8.3 Hz, 1H), 7.87 (d, J = 8.3 Hz, 1H), 7.50 (t, J = 7.7 Hz, 1H), 7.25–7.29 (m, 1H); 13 C{ 1 H} NMR (100 MHz, CDCl 3 ): δ 153.1, 142.0, 133.5, 129.2, 125.6, 86.3; MS (EI) [M] + m / z = 249.…”

Recent Advances in Transition-Metal-Catalyzed Iodination of Arenes

“…The challenges of developing a general metal-catalyzed iododecarboxylation reaction of aromatic carboxylic acids have been summarized in a very recent paper by the Cai research group who also report a copper-mediated method for this transformation. 75 They found that electron-deficient aromatic carboxylic acids bearing ortho-nitro groups could undergo efficient iododecarboxylation under aerobic conditions in the presence of stoichiometric amounts of copper(I) iodide, while electron-rich variants required the addition of catalytic palladium acetate to facilitate the transformation (Scheme 29). Heteroaromatic carboxylic acids, including benzofurans, benzothiofurans, and indoles, also gave iodinated products under these conditions.…”

Decarboxylative Bromination of Heteroarenes: Initial Mechanistic Insights

“…8 There are several reported methods for performing decarboxylative halogenation on aromatic substrates, but they often rely on metal catalysts, require high reaction temperatures, or are unselective. [9][10][11] Recent reports by Larrosa and co-workers have advanced this area of research, but their method requires stoichiometric quantities of a base and relatively high reaction temperatures. 12,13 We recently reported a metal-free selective decarboxylative halogenation of heteroaromatic compounds under mild conditions (Scheme 1).…”