Metal-catalyzed carbon-sulfur bond formation.

In organic synthetic reactions, the scope and application of organosulfur chemistry have increased tremendously since sulfur-containing groups serve an important auxiliary function in synthetic sequences.1 Illustrative examples are the reversal of polarity (Umpolung), the enhancement of the acidity of C-H bonds, and the transfer of chirality from sulfur to carbon.2 On the other hand, transition metal complexcatalyzed reactions have made a great contribution to the recent growth of organic synthesis,3 and a wide variety of synthetic transformations with combination of mainly group 8-10 transition metal catalysts with heteroatom-containing compounds such as silicone,4 tin,5 and boron6 compounds is well established. Considerable attention has also been focused on sulfur-containing transition metal complexes as model compounds of both active sites of natural enzymes7 and catalytic metal surfaces.8 However, transition metal complex-catalyzed synthetic reactions using sulfur-containing compounds remain open to study, since sulfur-containing compounds have long been known to act as catalyst poisons because of their strong coordinating and adsorptive properties and often rendered the catalytic reactions totally ineffective.9 In the past decade, the progress in organometallic chemistry has been to overcome the problems such as mismatched combination of transition metal catalysts with sulfur-containing compounds, and several useful transformations of sulfur-containing compounds using transition metal catalysts have been developed.10 In this article, transition metal complex-catalyzed organosulfur chemistry leading to selective formation of carbon-sulfur bonds is reviewed with an emphasis on recent progress.11 Although numerous carbonsulfur bond forming reactions on the transition metal complexes as a stoichiometric reaction have been reported, the present article surveys only the novel transition metal complex-catalyzed reactions which will open up new opportunities in organosulfur chemistry.