Catalytic Ring Expansion of Vinyl Oxetanes: Asymmetric Synthesis of Dihydropyrans Using Chiral Counterion Catalysis
作者:Boying Guo、Gregg Schwarzwalder、Jon T. Njardarson
DOI:10.1002/anie.201201367
日期:2012.6.4
Acid Showdown! The first catalyticring 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.