Rhodium‐Catalyzed Intramolecular [5+2] Cycloaddition of Inverted 3‐Acyloxy‐1,4‐enyne and Alkyne: Experimental and Theoretical Studies

By switching the position of the alkene and alkyne, a new type of 3-acyloxy-1,4-enyne (ACE) five-carbon building block was developed for Rh-catalyzed intramolecular [5+2] cycloaddition. An electron-withdrawing acyl group on the alkyne termini of the ACE was essential for a regioselective 1,2-acyloxy migration. This new method provided bicyclic [5.3.0]decatrienes that are different from previous methods because of the positions of the alkenes and the acyloxy group. Multiple mechanistic pathways become possible for this new [5+2] cycloaddition and they are investigated by computational studies.