Synthesis of Linear (Z)-α,β-Unsaturated Esters by Catalytic Cross-Metathesis. The Influence of Acetonitrile

• Published in: Angewandte Chemie Vol. 128; no. 42; pp. 13404 - 13408
• Main Authors: Yu, Elsie C., Johnson, Brett M., Townsend, Erik M., Schrock, Richard R., Hoveyda, Amir H.
• Format: Journal Article
• Language: English
• Published: Blackwell Publishing Ltd 10.10.2016
• Subjects: Acetonitrile; Alkene; Catalysis; Catalysts; Enoate; Esters; Katalyse; Kreuzmetathese; Molybdän; Olefins; Terminals; Transformations; Utilities
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201608087

Kinetically controlled catalytic cross‐metathesis reactions that generate (Z)‐α,β‐unsaturated esters selectively are disclosed. A key finding is that the presence of acetonitrile obviates the need for using excess amounts of a more valuable terminal alkene substrates. On the basis of X‐ray structure and spectroscopic investigations a rationale for the positive impact of acetonitrile is provided. Transformations leading to various E,Z‐dienoates are highly Z‐selective as well. Utility is highlighted by application to stereoselective synthesis of the C1–C12 fragment of biologically active natural product (−)‐laulimalide. Lewis‐Base benötigt: Die ersten Beispiele von Z‐selektiven katalytischen Kreuzmetathesen unter Bildung von α,β‐ungesättigten Estern werden vorgestellt. Die Gegenwart eines Organonitrils ist für hohe Effizienzen erforderlich. Studien zur Aufklärung der Rolle der Lewis‐Base, Reaktionen zur Bildung von E,Z‐Dienoaten und die Anwendung in der Synthese des C1‐C12‐Segments von Laulimalid werden beschrieben.