Unexpected Tandem Sonogashira-Carbopalladation-Sonogashira Coupling Reaction of Benzyl Halides with Terminal Alkynes: A Novel Four-Component Domino Sequence to Highly Substituted Enynes

Unexpected reactivity of benzyl halides with 1-alkynes in Sonogashira reaction promotes in a single-step process the construction of three carbon-carbon bonds regio- and stereoselectively and afforded highly substituted enynes in fair to good yields. The formation of the coupling adduct in this palladium-mediated four-component domino procedure is rationalized by an unprecedented tandem Sonogashira benzylpalladation Sonogashira sequence.