Three-Component Synthesis of Substituted Azepines by Gold/Magnesium Orthogonal-Relay Catalysis

A three-component one-pot synthesis of substituted azepines was realized by gold/magnesium orthogonal relay catalysis. The one-pot synthesis involves simply mixing and heating propiolates, imines, and activated cyclopropanes to initiate a gold-catalyzed aza-enyne metathesis between propiolates and imines, followed by a magnesium-catalyzed [4+3] cycloaddition reaction of the resultant 1-azabutadienes and the cyclopropanes, yielding substituted azepines. The substituted azepines including 22 derivatives could be successfully prepared in good to excellent yield (61–95%). The reaction was also conducted on one-gram scale.