An Efficient Solvent-Free Microwave-Assisted Synthesis of Cinnamamides by Amidation Reaction Using Phenylboronic Acid/Lewis Base Co-catalytic System
Abstract
A microwave-assisted dehydrative amide condensation reaction is reported as an efficient access to cinnamamide derivatives under solvent-free conditions. This protocol between conjugated carboxylic acids and amines is based on the use of a co-catalytic system, including the presence of the commercially available phenylboronic acid and 4-( N , N -dimethylamino)pyridine N -oxide (DMAPO), with a complete chemoselectivity in favor of the corresponding alpha,beta-unsaturated amides. The implementation of the reaction needs no special precaution, and less reactive amines, such as substituted anilines, are also efficient under these conditions. A series of novel conjugated amides have been evaluated for their cytotoxic activities against several human cancer cell lines.