Tandem Pd-Catalyzed Cyclization/Coupling of Non-Terminal Acetylenic Activated Methylenes with (Hetero)Aryl Bromides

Abstract
We report a new method for a tandem Pd-catalyzed intramolecular addition of active methylene compounds to internal alkynes followed by coupling with aryl and heteroaryl bromides. Highly substituted vinylidenecyclopentanes were obtained with good yields, complete selectivity, and excellent functional group tolerance. A plausible mechanism, supported by DFT calculations, involves the oxidative addition of bromoarene to Pd(0), followed by cyclization and reductive elimination. The excellent regio- and stereoselectivity arises from the 5-exo-dig intramolecular addition of the enol form of the substrate to alkyne activated by the π-acidic Pd(II) center, postulated as the rate-determining step.
Funding Information
  • National Science Center (2016/22/E/ST5/00537)
  • Wroclaw Centre for Networking and Supercomputing (518)

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