Palladium-Catalyzed Aryl Iodide Carbonylation as a Route to Imidazoline Synthesis: Design of a Five-Component Coupling Reaction

摘要

Since Heck's initial discovery in 1974, the palladium-catalyzed carbonylation of aryl halides has emerged as an important approach to construct carbonyl-containing compounds. In contrast to the traditional use of carboxylic acids to form nucleophile-acyl bonds, which often require the conversion of the acid into a more reactive unit with harsh substrates (e.g. acid chlorides, using thionyl or oxalyl chloride), or the use of stoichiometric coupling reagents (e.g. DCC, HOBt/HOAt), aryl halide carbonylation generates these same products with catalytic palladium and a cheap and abundant carbon source, CO. In this regard, this palladium-catalyzed reaction can be considered an efficient and green alternative to generating electrophilic acyl analogues to acid chlorides in the form of palladium intermediate 1 (Scheme 1).