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

High Resolution Image Download MS PowerPoint Slide 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.