Metal- and Solvent-Free Synthesis of m -Terphenyls by an Iodine-Catalyzed Tandem Formal [3+3]-Cycloaddition/Oxidation.

A tandem formal [3+3]-cycloaddition/oxidation between chalcones and β-enamine esters, employing iodine as a catalyst, was developed for the construction of various substituted m -terphenyls. A wide range of chalcones and β-enamine esters were tested under metal- and solvent-free conditions for the synthesis of substituted m -terphenyls in good to excellent yields in the presence of sulfur as an oxidant. This reaction proceeds with the formation of four new bonds and one new ring, with a high atom economy. [ABSTRACT FROM AUTHOR]