Activation and reactivity of Group 16 inter-element linkage — transition-metal-catalyzed reactions of thiols and selenols

This review deals with new synthetic methods for introducing Group 16 elements into organic molecules, especially, synthetic reactions based on the activation of Group 16 heteroatom compounds by transition metal catalysts. In these transition-metal-catalyzed reactions, metal chalcogenides (RY-MLn, Y=S, Se) play an important role. Chalcogen compounds with inter-element linkage such as SS, SeSe, SeSi, etc. add to terminal alkynes regio- and stereoselectively in the presence of palladium(0) catalyst. The addition of thiols and selenols to alkynes can be catalyzed by a lot of transition metal catalysts. In the presence of Pd(OAc)2, alkynes undergo Markovnikov addition with thiols, whereas the RhCl(PPh3)3-catalyzed reaction of alkynes provides anti-Markovnikov adducts regio- and stereoselectively. Moreover, the introduction of carbon monoxide into these transition-metal catalyzed addition reaction systems leads to the development of novel carbonylation reactions with simultaneous introduction of chalcogen functions.