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Synlett
DOI: 10.1055/a-2659-8340
Letter
Alkynes in Organic Synthesis

Asymmetric Isochalcogenourea-Catalyzed Synthesis of 3,4-Dihydropyrans via (4+2)-Cycloadditions of Ethyl But-3-ynoate with Michael Acceptors

Mario Hofer‡
Institute of Organic Chemistry, Johannes Kepler University Linz, Linz, Austria
,
Magdalena Piringer‡
Institute of Organic Chemistry, Johannes Kepler University Linz, Linz, Austria
,
Anna Scheucher‡
Institute of Organic Chemistry, Johannes Kepler University Linz, Linz, Austria
,
Lukas S. Vogl‡
Institute of Organic Chemistry, Johannes Kepler University Linz, Linz, Austria
,
Mario Waser 
Institute of Organic Chemistry, Johannes Kepler University Linz, Linz, Austria
› Author Affiliations
Funding Information This work was funded by the Austrian Science Funds (FWF): Project No. P36004 (10.55776/P36004; financial support was also obtained through the matching funds program by the Austrian National Foundation for Research, Technology and Development, and the Research Department of the State of Upper Austria) is gratefully acknowledged.
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Abstract

We herein report the use of ethyl but-3-ynoate as a C2 building block for asymmetric (4+2)-heterocycloadditions with various Michael acceptors. Upon using chiral isochalcogenoureas as Lewis base catalysts, these reactions can be carried out with good-to-excellent control of the regioselectivity, diastereoselectivity, and enantioselectivity.

Keywords

Organocatalysis - Lewis bases - Isochalcogenoureas - Cycloadditions - Alkynes - Heterocycles

Supplementary Material



Publication History

Received: 23 May 2025

Accepted after revision: 18 July 2025

Accepted Manuscript online:
18 July 2025

Article published online:
18 August 2025

© 2025. Thieme. All rights reserved.

Georg Thieme Verlag KG
Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany

 

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