Get access

Catalytic Ring Expansion of Vinyl Oxetanes: Asymmetric Synthesis of Dihydropyrans Using Chiral Counterion Catalysis


  • We thank the NSF (CHE-0848324) and the University of Arizona for financial support.


original image

Acid Showdown! The first catalytic ring expansion of vinyl oxetanes to 3,6-dihydro-2H-pyrans is described. Copper(II) triflate emerged as the best catalyst for this new transformation, which has broad scope as demonstrated by the eighteen examples included. The symmetric vinyl oxetane substrate can be asymmetrically desymmetrized when using either chiral Lewis or Brønsted acids as catalysts.