Dibenziodolium and diphenyliodonium triflates display high catalytic activity for the multicomponent reaction that leads to a series of imidazopyridines. Density functional theory (DFT) calculations indicate that both the salts can play the role of hybrid hydrogen- and halogen-bond-donating organocatalysts, which electrophilically activate the carbonyl and imine groups during the reaction process. The ortho-H atoms in the vicinal position to the I atom play a dual role: forming additional noncovalent bonds with the ligated substrate and increasing the maximum electrostatic potential on the σ-hole at the iodine atom owing to the effects of polarization. Dibenziodolium triflate exhibits higher catalytic activity, and the results obtained from 1H nuclear magnetic resonance (NMR) titrations, in conjunction with those from DFT calculations, indicate that this could be explained in terms of the additional energy required for the rotation of the phenyl ring in the diphenyliodonium cation during ligation of the substrate.

The most promising types of iodoazolium compounds exhibiting high catalytic activity toward halogen abstraction and carbonyl activation are highlighted.

The combination of experimental data and results of DFT calculations indicates that the catalytic activity of chalconium and halonium salts serving as sigma-hole donating organocatalysts cannot be clearly estimated via...

A four-component one-pot reaction proceeds very rapidly under mild conditions and gives the heterocyclic systems in good yields.

Kinetic data and computational study indicate that in the solution, pyrazole-containing iodolium salts and silver(I) center bind each other, and such interplay significantly affect the total catalytic activity of mixture of these Lewis acids compared with separate catalysis of the reactions required electrophilic activation of carbonyl, imino group, or triple CC bond. Moreover, the kinetic data and 1H NMR monitoring indicate that such cooperation results in prevention of decomposition of the organocatalysts by the silver(I) center during the reaction progress. XRD study indicates that in the solid state, the iodolium triflates and silver(I) triflate associate each other to give the complex species featuring triflate-bridged iodine(III) and silver(I) centers: a rare example of square-planar silver(I) complex and pentacoordinated trigonal bipyramidal dinuclear silver(I) complex.