Phosphine‐Catalyzed Tandem Annulation/Rearrangement Reaction of Enynes with N‐Tosylimines

Abstract A phosphine‐catalyzed tandem annulation/rearrangement reaction of yne‐enones with N ‐tosylimines has been developed, which proceeds well to afford the conjugated imines in moderate to high yields as single geometric isomer. Under mild reaction conditions, this reaction shows good tolerance for a variety of yne‐enones and N ‐tosylimines. This article provides 26 examples with yields up to 94% and diastereoselectivity greater than 20:1. The scale‐up reaction and further transformations were also successful, making it a powerful tool for the synthesis of conjugated imine derivatives as single geometric isomers. In addition, a reasonable reaction mechanism involving [2 + 2] cycloaddition and rearrangement is proposed.