Stereospecific Synthesis of Cyclohexenone Acids by [3,3]-Sigmatropic Rearrangement Route

J Org Chem. 2023 Sep 15;88(18):12914-12923. doi: 10.1021/acs.joc.3c00757. Epub 2023 Sep 1.

Abstract

Herein we report a modular synthetic method for the preparation of diaryl-substituted cyclohexenone acids starting from phenyl pyruvate and suitable enones. When the reaction is carried out in alkaline tert-butanol or toluene solutions in microwave-assisted conditions mainly anti configuration products are obtained with up to 86% isolated yield. However, when the reaction is carried out in alkaline water, a mixture of products with anti and syn conformations is obtained with up to 98% overall isolated yield. Mechanistically the product with anti conformation forms by a hemiketal-oxy-Cope type [3,3]-sigmatropic rearrangement-intramolecular aldol condensation route and syn product by an intermolecular aldol condensation-electrocyclization (disrotatory type) route.