Chemoselective reductions and iodinations using titanium tetraiodide

Titanium(IV) halides are extensively used in carboncarbon bond forming reactions as a Lewis acid and low valent titanium halides promote reductive coupling reactions of carbonyl compounds. In most of these reactions, ligands of titanium halides are chloride or bromide. On the other hand, titanium(IV) tetraiodide had been rarely used in organic synthesis until the late 1990s. Since 2000 several useful synthetic reactions have been developed utilizing a moderate Lewis acidity, reducing and iodination abilities of titanium(IV) tetraiodide. This digest summarizes examples of chemoselective reductions and iodinations using titanium(IV) tetraiodide (TiI4).