Ene-Allenes: Access from Dialkynes by an Intramolecular <i>anti</i> -Carbopalladation Cascade

Herein, an intramolecular palladium-catalyzed cascade reaction is reported consisting of both formal <i>anti</i>-carbopalladation and <i>syn</i>-carbopalladation of internal alkynes. This process leads to two new carbon-carbon bonds across the first double bond formed. The cascade is terminated by β-hydride elimination from the emerging vinyl Pd(II) complex. As a result, di-, tri-, and tetrasubstituted ene-allenes embedded in an oligo(hetero)cyclic ring system are synthesized in yields of up to 73%.