Chiral Lewis Base-Catalysed Asymmetric Syntheses of Benzo-fused ϵ-Lactones

Lotte Stockhammer; Maximilian Radetzky; Syeda Sadia Khatoon; Matthias Bechmann; Mario Waser

doi:10.1002/ejoc.202300704

Chiral Lewis Base-Catalysed Asymmetric Syntheses of Benzo-fused ϵ-Lactones

European J Org Chem. 2023 Oct 16;26(39):e202300704. doi: 10.1002/ejoc.202300704. Epub 2023 Sep 18.

Authors

Lotte Stockhammer¹, Maximilian Radetzky¹, Syeda Sadia Khatoon¹, Matthias Bechmann¹, Mario Waser¹

Affiliation

¹ Institute of Organic Chemistry Johannes Kepler University Linz Altenbergerstrasse 69 4040 Linz Austria.

Abstract

We herein report a two-step protocol for the asymmetric synthesis of novel chiral benzofused ϵ-lactones starting from O-protected hydroxymethyl-para-quinone methides and activated aryl esters. By using chiral isothiourea Lewis base catalysts a broad variety of differently substituted products could be obtained in yields of around 50 % over both steps with high levels of enantioselectivities, albeit low diastereoselectivities only.

Keywords: Lewis base catalysis; asymmetric organocatalysis; cyclizations; lactones; quinone methides.