The use of dichloromaleic and bromomaleic anhydrides in the synthesis of lactones by the intramolecular Diels–Alder reaction

Abstract

Reaction of (E)-penta-2, 4-dien-1-ol with dichloromaleic anhydride gives an unstable triene, which on heating undergoes an Intramolecular Diels–Alder cyclisation to give a bicyclic acid, which on dechlorodecarboxylation affords an unsaturated bicyclic lactone. Reaction of (E)-penta-2, 4-dien-1-ol with half-esters derived from dichloromaleic anhydride permits similar cyclisation to afford bicyclic esters. Elaborations of these adducts via reduction and dehydrochlorination reactions are described. Similar adducts are prepared from bromomaleic anhydride and are further elaborated. From 3-vinylcyclohex-2-enol via the intermediary of triene precursors derived from dichloromaleic anhydride, bromomaleic anhydride, and half-esters of malefic and fumaric acid tricyclic adducts are obtained in certain cases. These cyclisations and the subsequent elaborations are discussed with respect to their synthetic potential and their relation to related recently reported examples.