Hydrogen bonding in organic synthesis. Part 7. Intermolecular self-condensation of some enolisable ketones in the presence of fluoride

Abstract

A number of enolisable ketones undergo intermolecular self-condensation and cyclisation in the presence of fluoride. Fluoride encourages the enolisation of ketones, thereby providing an hydroxylic electron-acceptor site capable of forming strong H-bonds with the fluoride anion. The reactions of the H-bond-activated ketones are usually characteristic of enolate anions: aldol-type condensations and Michael reactions are observed.