Asymmetric Nazarov Cyclizations of Unactivated Dienones by Hydrogen‐Bond‐Donor/Lewis Acid Co–Catalyzed, Enantioselective Proton‐Transfer
作者:Jan B. Metternich、Martin Reiterer、Eric N. Jacobsen
DOI:10.1002/adsc.202000831
日期:2020.10.6
cyclization catalyzed by chiral hydrogen‐bond‐donors in concert with silyl Lewis acids. The developed transformation provides access to tri‐substituted cyclopentenones in high levels of enantioselectivity (up to 95% e.e.) from a variety of simple unactivated dienones. Kinetic and mechanistic studies are consistent with a reversible 4π‐electrocyclization C−C bond‐forming step followed by rate‐ and enantio‐determining
Synthesis of α,β-Disubstituted Acrylates via Galat Reaction
作者:Tania Xavier、Sylvie Condon、Christophe Pichon、Erwan Le Gall、Marc Presset
DOI:10.1021/acs.orglett.9b02291
日期:2019.8.2
Galat reactions between aldehydes and substituted malonic acids half oxyester were found to be efficiently catalyzed by morpholine in refluxing toluene. This transformation allows the stereoselective synthesis of diverse alpha,beta-disubstituted acrylates in moderate to good yields. This method constitutes an attractive alternative to existing methods in terms of scope and eco-compatibility.