Zusammenfassung
In the field of asymmetric copper-catalyzed 1,4-addition reactions new applications were established using triorganoaluminum reagents in etheral solvents. This raised the question of whether phosphoramidite copper complexes have similar structures and aggregation levels in THF compared to noncoordinating solvents such as CD2Cl2. Therefore, NMR spectroscopic investigations of the precatalytic ...
Zusammenfassung
In the field of asymmetric copper-catalyzed 1,4-addition reactions new applications were established using triorganoaluminum reagents in etheral solvents. This raised the question of whether phosphoramidite copper complexes have similar structures and aggregation levels in THF compared to noncoordinating solvents such as CD2Cl2. Therefore, NMR spectroscopic investigations of the precatalytic structure of phosphoramidite copper complexes in THF-d8 were performed. Combined low-temperature studies, spectra simulations, and a detailed integral analysis indicated [(CuIL)(CuIL2)4] as precatalyst in THF. This confirms the mixed trigonal/tetrahedral coordination of the copper atoms in phosphoramidite copper complexes as a more general motif. In addition, highly aggregated complexes might be more probable than expected even in THF.
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