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キーワード:
Au(I)-catalysis; Buchwald phosphines; cycloisomerizations; ligand design; α-cationic phosphines
要旨:
The synthesis and characterization through NMR and X-ray
crystallography of a series of N-arylpyridiniophosphines and their
corresponding Au(I)-derivatives are reported. Because of their acceptor
properties, pyridiniophosphines efficiently enhance the electrophilicity of
the Au atom in the complexes they form. In our study, this is translated
into higher reactivity of the corresponding Au catalysts, which is
demonstrated in two mechanistically differentiated cycloisomerizations.
Moreover, the steric protection and probably also the electronic
stabilization provided by the N-aryl substituents make the active Au-species
more robust and slow down its rate of decay. This allows for an
appreciable reduction of the catalyst loadings.
