Ionic liquid supports stable under conditions of peptide couplings, deprotections and traceless Suzuki reactions

Ionic liquid supports (ILS) functionalized with carboxylic, alcoholic or amino groups were synthesized, based on 1-methylimidazolium and pyridinium cations, and bromide, chloride, iodide and tetrafluoroborate anions. These reactive ionic liquids were fully characterized by NMR and HRMS. Ionic liquids based on 1-(6-aminohexyl)-3-methylimidazolium iodide have been used in the conditions of peptide chemistry such as coupling and deprotection reactions. A method for attaching ( bromophenyl) silanes to the ionic liquid supports was also developed to introduce traceless linkers. An ionic liquid with attached bromobenzene was reacted with ArB(OH)(2) under the Suzuki cross-coupling conditions and the resulting compound was cleaved by bromodesilylation with Br-2/pyridine to give the substituted products in good yields. The substrate loading of the ILS is high and can be tuned to between 2.5 and 5.0 mmol/g.