Insight into the Activation of In Situ Generated Chiral Rh^I Catalysts and Their Application in Cyclotrimerizations

We report a detailed study concerning the efficient generation of highly active chiral rhodium complexes of the general structure [Rh(diphosphine)(solvent)₂ ]⁺ as well as their exemplary successful utilization as catalysts for cyclotrimerizations. Such solvent complexes could likewise be prepared from novel ammonia complexes of the type [Rh(diphosphine)(NH₃ )₂ ]⁺ . A valuable, feasible approach to generate novel chiral Rh^I complexes was found by in situ generation from Wilkinson's catalyst [RhCl(PPh₃ )₃ ] with chiral P,N ligands. The generated catalysts led to moderate to good enantioselectivities and excellent yields in the cyclotrimerizations of triynes, showcasing their usefulness in the synthesis of axially chiral benzene derivatives.