Brønsted Acid Catalyzed Enantioselective Semipinacol Rearrangement for the Synthesis of Chiral Spiroethers

Abstract

Keine halben Sachen: Die im Titel genannte Umlagerung von 2‐Oxoallylalkoholen 1 in Gegenwart einer katalytischen Menge der chiralen Phosphorsäure (R)‐2 a oder ihres Silbersalzes (R)‐2 b liefert die Spiroether 3 in enantiomerenreiner Form.

Asymmetric Ion‐Pairing Catalysis

“…[70] The authors also designed this reaction on the premise that protonation of vinyl ether starting materials by a chiral phosphoric acid should result in the formation of chiral oxocarbenium•phosphate ion pair intermediates. By employing the silver salt of 14a as a precatalyst, mild conditions were identified that are optimal for most substrates.…”

Asymmetrische Gegenanionen‐vermittelte Katalyse: Konzept, Definition und Anwendungen

“…[61] Das erste Beispiel einer asymmetrischen Gegenanionen-vermittelten Lewis-Säurekatalyse wurde 2007 von Antilla et al vorgeschlagen. [61] Das erste Beispiel einer asymmetrischen Gegenanionen-vermittelten Lewis-Säurekatalyse wurde 2007 von Antilla et al vorgeschlagen.…”

Organocatalytic Asymmetric Fluorination/Semipinacol Rearrangement: An Efficient Approach to Chiral β‐Fluoroketones

“…[11] Recently, our research group and that of others have reported some examples of asymmetric bromination/semipinacol rearrangement reactions that are catalyzed by cinchona-alkaloid derivatives. [12] In light of our previous results, combined with our long-standing interest in semipinacol-rearrangement reactions, [13,14] we hypothesized that the fluorination/semipinacol rearrangement reaction could also be catalyzed by cinchona-alkaloid derivatives in an asymmetric manner (Scheme 2). Herein, we present our preliminary results on this reaction.…”