Synthesis and Single-Electron Oxidation of Bulky Bis(m-terphenyl)chalcogenides: The Quest for Kinetically Stabilized Radical Cations.

Sterically encumbered bis(m-terphenyl)chalcogenides, (2,6-Mes2 C6 H3 )2 E (E=S, Se, Te) were obtained by the reaction of the chalcogen tetrafluorides, EF4 , with three equivalents of m-terphenyl lithium, 2,6-Mes2 C6 H3 Li. The single-electron oxidation of (2,6-Mes2 C6 H3 )2 Te using XeF2 /K[B(C6 F5 )4 ] afforded the radical cation [(2,6-Mes2 C6 H3 )2 Te][B(C6 F5 )4 ] that was isolated and fully characterized. The electrochemical oxidation of the lighter homologs (2,6-Mes2 C6 H3 )2 E (E=S, Se) was irreversible and impaired by rapid decomposition.

Two-step continuous-flow synthesis of 6-membered cyclic iodonium salts via anodic oxidation.

We describe a multi-step continuous-flow procedure for the generation of six-membered diaryliodonium salts. The accompanying scalability and atom economy are significant improvements to existing batch methods. Benzyl acetates are submitted to this two-step procedure as highly available and cheap starting materials. An acid-catalyzed Friedel-Crafts alkylation followed by an anodic oxidative cyclization yielded a defined set of cyclic iodonium salts in a highly substrate-dependent yield.

One-Pot Synthesis and Conformational Analysis of Six-Membered Cyclic Iodonium Salts.

Two one-pot procedures for the construction of carbon-bridged diaryliodonium triflates and tetrafluoroborates are described. Strong Brønsted acids enable the effective Friedel-Crafts alkylation with diversely substituted o-iodobenzyl alcohol derivatives, providing diphenylmethane scaffolds, which are subsequently oxidized and cyclized to the corresponding dibenzo[b,e]iodininium salts. Based on NMR investigations and density functional theory (DFT) calculations, we could verify the so-far-undescribed existence of two stable isomers in cyclic iodonium salts substituted with aliphatic side chains in the carbon bridge.