Radical Additions of Thiols to Alkenes and Alkynes in Ionic Liquids

The radical addition of thiols to double and triple carbon-carbon bonds was examined in typical ionic liquids ([bmim][PF6], [bmim][Tf2N], and [bmim][BF4]) under different temperature/initiator conditions (i.e. 80-100 °C / AIBNVAZO ®, r.t. / triethylborane, r.t. / AIBN / UV radiation, r.t. / photoinitiator / UV radiation). All the addition products were usually obtained with high efficiencies and very good recyclability of the ionic liquid. In some cases, small but significant differences were noticed by changing the reaction medium from benzene to a ionic liquid. The possibility of applying this procedure to click-chemistry reactions with thiols/alkenes of biological interest is also discussed.