Catalytic Enantioselective [4+2] Cycloadditions of Salicylaldehyde Acetals with Enol Ethers

Xiaojun Hu; Zhengbo Zhu; Zhongzheng Li; Alafate Adili; Minami Odagi; Khalil A Abboud; Daniel Seidel

doi:10.1002/anie.202315759

Catalytic Enantioselective [4+2] Cycloadditions of Salicylaldehyde Acetals with Enol Ethers

Angew Chem Int Ed Engl. 2024 Jan 22;63(4):e202315759. doi: 10.1002/anie.202315759. Epub 2023 Dec 20.

Authors

Xiaojun Hu¹, Zhengbo Zhu¹, Zhongzheng Li¹, Alafate Adili¹, Minami Odagi^{1

2}, Khalil A Abboud³, Daniel Seidel¹

Affiliations

¹ Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, FL 32611, USA.
² Department of Biotechnology and Life Science, Graduate School of Technology, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei city, 184-8588, Tokyo, Japan.
³ Center for X-ray Crystallography, Department of Chemistry, University of Florida, Gainesville, FL 32611, USA.

PMID: 38055210
DOI: 10.1002/anie.202315759

Abstract

A readily accessible conjugate-base-stabilized carboxylic acid (CBSCA) catalyst facilitates highly enantioselective [4+2] cycloaddition reactions of salicylaldehyde-derived acetals and cyclic enol ethers, resulting in the formation of polycyclic chromanes with oxygenation in the 2- and 4-positions. Stereochemically more complex products can be obtained from racemic enol ethers. Spirocyclic products are also accessible.

Keywords: Asymmetric Catalysis; Brønsted Acid Catalysis; Chromanes; Ortho-Quinone Methides; [4+2] Cycloaddition.

Grants and funding

CHE-2154292/National Science Foundation