Unusual Skeletal Rearrangement of Unsaturated Seven‐Membered Lactams into Fused Pyrrolidinolactones

Abstract

AbstractUnsaturated ϵ‐lactams undergo a novel process involving a skeletal reorganization to give fused pyrrolidine‐lactones by reaction with aromatic α‐bromo ketones in the presence of 1,4‐diazabicyclo[2.2.2]octane and a base. The process involves the formation of an ammonium salt and subsequently a nitrogen ylide, which initiates the rearrangement reaction. This species reduces undesired side‐reactions such as double‐bond shifts or Morita–Baylis–Hilman‐type processes. The resulting products are structurally related to kainoids and the transformation of the lactone moiety in the rearranged product paves the way to the synthesis of these potentially bioactive natural products and their derivatives.