Stoichiometric and Catalytic C-C and C-H Bond Formation with B(C6 F5 )3 via Cationic Intermediates

Yashar Soltani; Lewis C Wilkins; Rebecca L Melen

doi:10.1002/anie.201704789

Stoichiometric and Catalytic C-C and C-H Bond Formation with B(C₆ F₅ )₃ via Cationic Intermediates

Angew Chem Int Ed Engl. 2017 Sep 18;56(39):11995-11999. doi: 10.1002/anie.201704789. Epub 2017 Aug 18.

Authors

Yashar Soltani¹, Lewis C Wilkins¹, Rebecca L Melen¹

Affiliation

¹ School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, Cymru/Wales, UK.

PMID: 28703388
DOI: 10.1002/anie.201704789

Abstract

This work showcases a new catalytic cyclization reaction using a highly Lewis acidic borane with concomitant C-H or C-C bond formation. The activation of alkyne-containing substrates with B(C₆ F₅ )₃ enabled the first catalytic intramolecular cyclizations of carboxylic acid substrates using this Lewis acid. In addition, intramolecular cyclizations of esters enable C-C bond formation as catalytic B(C₆ F₅ )₃ can be used to effect formal 1,5-alkyl migrations from the ester functional groups to unsaturated carbon-carbon frameworks. This metal-free method was used for the catalytic formation of complex dihydropyrones and isocoumarins in very good yields under relatively mild conditions with excellent atom efficiency.

Keywords: Lewis acids; boron; cyclization; homogeneous catalysis; tris(pentafluorophenyl)borane.