Palladium-Catalyzed Oxidative Ethoxycarbonylation of Aromatic C−H Bond with Diethyl Azodicarboxylate

• Published in: Journal of the American Chemical Society Vol. 130; no. 11; pp. 3304 - 3306
• Main Authors: Yu, Wing-Yiu, Sit, Wing Nga, Lai, Kin-Man, Zhou, Zhongyuan, Chan, Albert S. C
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 19-03-2008
• Subjects: Azo Compounds - chemistry; Carboxylic Acids - chemistry; Catalysis; Esters - chemical synthesis; Esters - chemistry; Molecular Structure; Organometallic Compounds - chemistry; Oxidation-Reduction; Palladium - chemistry; Stereoisomerism
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja710555g

This communication describes the Pd(OAc)2-catalyzed ethoxycarbonylation reactions of aromatic C−H bonds using diethyl azodicarboxylate (DEAD) together with Oxone or K2S2O8. Substrates such as 2-arylpyridines, pyrrolidinone, acetylindoline, quinoline, and oximes were ethoxycarbonylated with excellent chemo- and regioselectivities. The catalytic reaction is probably initiated by chelation-assisted cyclopalladation of the ortho-C−H bond. Preliminary studies suggested that reactive ethoxyacyl radicals generated from thermal decomposition of DEAD were involved in the ester formation.