Formal anti-Carbopalladation Reactions of Non-Activated Alkynes: Requirements, Mechanistic Insights, and Applications

Formal anti‐carbopalladation reactions of CC triple bonds are uncommon, but highly useful transformations. Alkynes can be designed to give anti‐carbopalladation products. Prerequisite is the exclusion of other reaction pathways to provoke the cis–trans isomerization of the syn‐carbopalladation intermediate. Detailed mechanistic studies of this crucial step by experimental and computational means were performed. Application of an intramolecular version for the synthesis of oligocyclic compounds and substituted dibenzofurans is also described. Reduced options: Diyne and enyne systems are designed that lead exclusively to formal anti‐carbopalladation reactions. A prerequisite is the absence of β‐hydrogen atoms that could offer other reaction channels. The mechanism is demonstrated by means of experiments as well as DFT calculations.