Lewis-Acid-Catalyzed (3+2)-Cycloadditions of Donor-Acceptor Cyclopropanes with Thioketenes

Grzegorz Mlostoń; Mateusz Kowalczyk; André U Augustin; Peter G Jones; Daniel B Werz

doi:10.1002/ejoc.202100879

Lewis-Acid-Catalyzed (3+2)-Cycloadditions of Donor-Acceptor Cyclopropanes with Thioketenes

European J Org Chem. 2021 Dec 14;2021(46):6250-6253. doi: 10.1002/ejoc.202100879. Epub 2021 Aug 25.

Authors

Grzegorz Mlostoń¹, Mateusz Kowalczyk¹, André U Augustin², Peter G Jones³, Daniel B Werz²

Affiliations

¹ University of Łodź Department of Organic & Applied Chemistry Tamka 12 91-403 Łodź Poland.
² Technische Universität Braunschweig Institute of Organic Chemistry Hagenring 30 38106 Braunschweig Germany.
³ Technische Universität Braunschweig Institute of Inorganic and Analytical Chemistry Hagenring 30 38106 Braunschweig Germany.

Abstract

The reactivity of donor-acceptor (D-A) cyclopropanes towards thioketenes was investigated. In a (3+2)-cycloaddition using Sc(OTf)₃ as a Lewis acidic catalyst, the corresponding exocyclic thioenol ethers (2-methylidene tetrahydrothiophenes) were formed in moderate to good yields. Unsymmetrical thioketenes provided E/Z mixtures at the double bond, with the Z isomer being preferred.

Keywords: Cycloaddition; D-A cyclopropanes; Lewis acids; Sulfur heterocycles; Thioketenes.