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Hydrocarbation of C[TRIPLE BOND]C Bonds: Quantification of the Nucleophilic Reactivity of Ynamides


  • We thank the Deutsche Forschungsgemeinschaft (SFB 749, Project B1) for financial support. Helpful discussions with Dr. J. Bartl, Dr. D. Stephenson, and Dr. A. R. Ofial are gratefully acknowledged.


Donor-substituted diarylcarbenium ions Ar2CH+ react with ynamides to give 1-amido-substituted allyl cations (α,β-unsaturated iminium ions). Kinetic studies show that these adducts, which correspond to the addition of a C[BOND]H bond across the C[TRIPLE BOND]C bond, are formed stepwise with initial formation of keteniminium ions and subsequent 1,3-hydride shifts. The linear correlations between the second-order rate constants (lg k2, 20 °C) with the electrophilicity parameters E of the diarylcarbenium ions allow us to include ynamides in our comprehensive nucleophilicity scale and thus predict potential electrophilic reaction partners.