Cyclopalladation of N-phenylbenzamides: Synthesis and structure of bimetallic palladium(II)-complexes

Three bimetallic palladium(II) complexes were generated by cyclopalladation of N-methyl-N-phenylbenzamide derivatives, substrates known to undergo oxidative intramolecular cross-coupling via palladium catalysis. These isolable Pd-complexes were characterized by X-ray crystallography. Stoichiometric and catalytic experiments with [(3-methoxy-N-methyl-N-phenylbenzamide)Pd(μ-TFA)]2 were investigated, and this palladium complex was found to be an effective precatalyst for oxidative cross-coupling.

Graphical abstractThree bimetallic palladium(II) complexes were generated by cyclopalladation of N-methyl-N-phenylbenzamide derivatives, substrates known to undergo oxidative intramolecular cross-coupling via palladium catalysis. These isolable Pd-complexes were characterized by X-ray crystallography. Stoichiometric and catalytic experiments with [(3-methoxy-N-methyl-N-phenylbenzamide)Pd(μ-TFA)]2 were investigated, and this palladium complex was found to be an effective precatalyst for oxidative cross-coupling.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► Synthesis of three palladacycles [(3-methoxy-N-methyl-N-phenylbenzamide)Pd(μ-TFA)]2 (3a), [(3-methoxy-N-methyl-N-(o-tolyl)benzamide)Pd(μ-TFA)]2 (3b) and [(3,4-dimethoxy-N-methyl-N-phenylbenzamide)Pd(μ-TFA)]2 (3c). ► X-ray crystal structures show five-membered benzamide palladacycles. ► Pd-complex 3a undergoes reductive elimination. ► Pd-complex 3a catalyzes intramolecular oxidative cross-coupling efficiently.