123-Triazolium-Derived Mesoionic Carbene LigandsBearing Chiral Sulfur-Based Moieties: Synthesis Catalytic Propertiesand Their Role in Chirality Transfer

摘要

1,2,3-Triazole-derived mesoionic carbenes (MICs) having a chiral sulfur functional group at the C5 position are easily available through a CuAAC between chiral alkynyl sulfoxides and different azides. The MICs form complexes with several metals (Au, Ag, Ir, Rh, and Ru) that are enantiomerically pure. Moreover, enantiomerically pure MIC sulfinilimines are obtained from the corresponding sulfoxide retaining the chirality. Through this article, the participation of sulfoxide moieties in different catalytic and chirality transfer processes, as well as in discovering mechanistically new processes will be shown. The role of the sulfur chiral moiety in catalytic cycloisomerization and cycloisomerization–dimerization processes using Au–MIC catalysts is dual. The sulfur functional group either stabilizes intermediates in the catalytic cycle, allowing for the reaction to occur or significantly increases the selectivity of the cyclization processes. 1,2,3-Triazole MICs having chiral sulfoxides at C5 are extremely efficient in preparing chiral at the metal complexes by C–H insertion processes. The chiral at the metal half-sandwichcomplexes, having the enantiopure sulfur chiral group unaltered, experiencesdifferent reactions with complete retention of the configuration.Finally, mechanistically new processes, like the desulfinilation of1,2,3-triazolium salts in Ag–MIC complexes have been uncovered.These still-nascent classes of compounds will offer opportunitiesfor the discovery of novel catalytic applications and to study newmechanistically sound processes.