ESI-MS Studies in Palladium-Catalyzed Alkynylation Reactions

Palladium-tellurium cationic intermediates 173,174, and 175 were observed in the mass spectra. It has been su ested that these were formed by ionization of the neutral species LnPdCl2. Several alkynylcopper species of type 177 were detected with the characteristic Cu isotopic pattern. Negative ion-mode ESI-MS( ) monitoring of the reaction failed to reveal any metal anions. 

Sonogashira cross-coupling is another typical palladium-catalyzed process consisting of the alkynylation of aryl or alkenyl halides in the presence of Cu(I) salts [46]. 

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