Synthesis of silyl-protected terminal thioalkyne-substituted tetraaryl imidazoles: utilization of Ag–Fe/ZSM-5 bimetallic nanooxides for cyclocondensation of polysubstituted imidazoles

Article abstract of DOI:10.1007/s11164-016-2787-1

An improved one-pot and ecofriendly approach to tri- and tetraaryl imidazoles through three- and four-component coupling reactions under neutral and solvent-less solid-phase conditions is presented. A series of nanosized Ag/metal oxide species on H–ZSM-5 support were tested in this procedure, with Ag–Fe/ZSM-5 bimetallic oxide nanoparticles exhibiting excellent catalytic activity for improved efficiency of the one-pot, multicomponent cyclocondensation reaction. The obtained bromoimidazole derivatives were converted into silyl-protected terminal alkynyl thiolate-substituted tetraaryl imidazoles by treatment with lithium 2,2,2-tris(trimethylsilyl)ethanedithioate, produced by reaction of organolithium reagent (Me₃Si)₃CLi with CS₂ at 0?°C. These novel and stable synthetic intermediates are potential compounds for functionalization of imidazoles.