Recent Advances in the Asymmetric Claisen Rearrangement Promoted by Chiral Organometallic Lewis Acids or Organic Brønsted-Lowry Acids

Enantioselective Sulfonium–Claisen Rearrangement with Cinnamyl Thioethers

“…Claisen rearrangement and its variations have served as key methods in the stereocontrolled assembly of complex organic structures. , Despite its long history, its catalytic enantioselective variant has been demonstrated only in a limited range of substrates (Scheme a) . Among them, α- and β-allyloxy acrylate analogs , that can be activated by transition-metal or hydrogen-bonding catalysts through bidentate binding have been the most commonly employed.…”

Copper(I)-Catalyzed Synthesis of Unsymmetrical All-Carbon Bis-Quaternary Centers at the Opposing α-Carbons of Cyclohexanones

“…Attempts to improve diastereoselectivity in the Claisen rearrangement was then carried out by screening various Lewis acid catalysts that could hypothetically serve either as an oxyphilic activator 13 or as a π-complex activator 14 to compound 12 . As shown in entries 1–3, BF 3 ·OEt 2 , AgOTf, and Cu(OTf) 2 caused decomposition.…”