Diiodoindium(Ⅲ) Cation, InI_2~+, a Potent Yneophile. Generation and Application to Cationic Cyclization by Selective π-Activation of C≡C

摘要

The removal of the iodide ion from indium triiodide by means of reactive Ag(Ⅰ) salts leads to the formation of the highly reactive ligandless cation InI_2~+, which is unusual in having two vacant low-lying p-orbitals. This bivalent Lewis acidity leads to an especially high affinity for the two orthogonal π-bonds of carbon-carbon triple bonds. Consequently, the double-coordinating InI_2~+ is an especially effective reagent for the selective activation of C≡C and the catalytic initiation of cationic cyclization processes. A number of such reactions are described to demonstrate synthetic utility.