The reactions of norbornyl-type cations derived from the reaction of silver toluene-4-sulphonate with 3-substituted 5-iodonorbornane-2,6-lactones

Abstract

A series of 3-phenyl- and 3-methyl-substituted 6-endo-hydroxy-5-exo-iodonorborn-2-endo-ylcarboxylic acid γ-lactones and the corresponding acetic acid δ-lactones have been prepared, and their reaction with silver toluene-4-sulphonate studied in acetonitrile solution. In each case the products formed have been isolated and identified, and shown to be derived from the initially formed norobornyl-type cation or the cation derived from Wagner–Meerwein rearrangement. The normal reaction of these cations is capture by toluene-4-sulphonate anion, but in certain cases the cations lose a proton to give an unsaturated or nortricyclene lactone. 3-exo-Substituents reduce the extent of the Wagner–Meerwein rearrangement to a varying degree.