Palladium‐Catalyzed Intramolecular Trost–Oppolzer‐Type Alder–Ene Reaction of Dienyl Acetates to Cyclopentadienes

Abstract

A new approach to the synthesis of highly substituted cyclopentadienes, indenes, and cyclopentene-fused heteroarenes by means of the Pd-catalyzed Trost–Oppolzer-type intramolecular Alder–ene reaction of 2,4-pentadienyl acetates is described. This unprecedented transformation combines the electrophilic features of the Tsuji–Trost reaction with the nucleophilic features of the Alder–ene reaction. The overall outcome can be perceived as a hitherto unknown “acid-free” iso-Nazarov-type cyclization. The versatility of this strategy was further demonstrated by the formal synthesis of paucifloral F, a resveratrol-based natural product.