Reversible Alkene Insertion into the Pd-N Bond of Pd(Ⅱ)- Sulfonamidates and Implications for Catalytic Amidation Reactions

摘要

Alkene insertion into Pd-N bonds is a key step in Pd-catalyzed oxidative amidation of alkenes. A series of well-defined Pd(II)-sulfonamidate complexes have been prepared and shown to react via insertion of a tethered alkene. The Pd-amidate and resulting Pd-alkyl species have been crystallographically characterized. The alkene insertion reaction is found to be reversible, but complete conversion to oxidative amination products is observed in the presence of O_2. Electronic-effect studies reveal that alkene insertion into the Pd-N bond is favored kinetically and thermodynamically with electron-rich amidates.