Intramolecular Formal anti-Carbopalladation/Heck Reaction: Facile Domino Access to Carbo- and Heterooligocyclic Dienes

An intramolecular domino process consisting of a formal anti-carbopalladation followed by Heck reaction is realized. Complex oligo(hetero)cyclic scaffolds are efficiently obtained in one synthetic step from easily obtainable enyne precursors. In contrast to common syn-carbopalladation reactions of alkyne units, the carbopalladation employed here is designed to afford an anti-arrangement of the two new substituents across the emerging double bond. A prerequisite is that the residues next to the alkyne should lack any beta-hydrogen atoms. The method paves the way to tri- and tetrasubstituted double-bond systems that have not been accessible by conventional Pd catalysis.